JPS6352710A - Tool using synthetic diamond monocrystal - Google Patents

Abstract

PURPOSE:To prevent uneven wear of tools by forming a rectangle so as to bring specific crystal faces to be two parallel crystal faces and setting a less wear resistant crystal orientation in the length direction and a more wear resistant crystal orientation in the breadth direction. CONSTITUTION:A synthetic diamond is cut to from a small monocrystal whose respective two parallel faces are a crystal face (110). Then, the two parallel faces are formed into a rectangular shape; in each face, a less wear resistant crystal orientation (100) and a more wear resistant crystal orientation (110) are set in the length and the breadth direction, respectively; a vertical hole is bored at the center. In that method, generated stresses reduce as the thickness of a diamond increases. Thus, a wear of a less wear resistant side is equalized to that of a more resistant side because the less wear resistant side in crystal orientations is thicker than the more wear resistant side. Therefore, uneven wear of tools is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention involves passing an object through a hole such as a wire drawing die for metal wire, a high-pressure water jet nozzle, etc., and processing it by receiving surface pressure from the inner surface of the hole. This invention relates to diamond tools, particularly 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 desired by the market, and the applicant's commercialization of synthetic diamonds 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,
The publication proposes a wire-drawing die using a synthetic diamond single crystal, and discloses a die that makes holes perpendicular to the crystal plane (100) or (111). 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 die 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.

By the way, since natural diamonds are subjected to melting action during the production process, they rarely have smooth crystal faces, but rather curved surfaces with a -+a roundness, and are irregular in shape as shown in Figure 2. Therefore, when creating the 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, depending on the shape and ease of polishing,
In reality, it is difficult to determine whether the crystal plane is (1,10) or (111), and the upper and lower surfaces are 5.5
It is difficult to arrange all of the crystals in a specific crystal plane, and only products with large variations in quality can be produced.

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 (1,00) is inferior and is therefore avoided. However, it has not been sufficiently clear which is better, (1, 10) or (111), as the variation is larger.

Furthermore, as shown in Figure 3, each crystal plane has anisotropy in hardness and wear, with the long direction of the arrow being relatively soft and easily worn, and the short direction of the arrow being hard and not easily worn. . Therefore, as shown in Figure 4, the tendency of wear of the die hole perpendicular to the crystal plane is relatively easy to wear in the <100> direction of the arrow on the (110) plane, and in the 110> direction that is not perpendicular to this. Resistant to wear and exhibits oval wear. (In Figure 4 [10
Opposite directions such as 0) and (100) or (110:l and (TIO)) are <100> or <1.1, respectively.
The (100) plane (represented by O) is relatively easy to wear in the four directions of the arrows, and exhibits square wear. Also (11,1)
The surface wears relatively easily in the three directions indicated by the arrows, exhibiting triangular wear. In this way, natural diamond has different wear tendencies depending on its crystal plane and crystal orientation, and although its wear resistance as a wire drawing die is much higher than that of cemented carbide, etc., it gradually develops uneven uneven wear. Synthetic diamond single crystals also have the same tendency to wear due to crystal planes and crystal orientations as in the case of natural diamonds described above.

Unlike natural diamond, synthetic diamond single crystals are synthesized by dividing large single crystals into small crystals.
Both upper and lower end faces that are parallel to each other are all specified crystal planes (110)
Furthermore, it is easy to make it into a regular polygon or circle that is symmetrical with respect to the central axis of the die hole perpendicular to the two lower end faces. Natural diamonds, on the other hand, are asymmetrical in this respect.

As shown in ``2'' below, synthetic diamond single crystals are made by aligning the upper and lower crystal planes and by making them symmetrical in shape, so that the stress generated by the internal pressure of the die during wire drawing can be suppressed over the entire circumference of the inner wall of the die. It can be made uniform and has an advantage over natural diamond in terms of reducing uneven wear, but it has not been able to control the tendency of wear due to the crystal orientation due to the crystallographic properties mentioned above.

[Means for solving problems]

In order to solve the above-mentioned problems in tools using natural diamond or synthetic Guyamond, this invention splits diamond synthesized under ultra-high pressure and high temperature, so that two parallel faces are both crystal planes (], 10 ), and the above two parallel planes are rectangular, and within that plane, the major axis direction is the crystal orientation <100>, which is easy to wear, and the minor axis direction is the crystal orientation, <110>, which is difficult to wear. The rectangle has a perpendicular hole in the center thereof, and the side surfaces are parallel to the central axis of the hole.

The details are detailed below.

To create a synthetic diamond single crystal at ultra-high pressure and high temperature, 0
．． A method is adopted in which a seed crystal with a size of about 5 wm is grown. If the single crystal is slightly larger than the seed crystal, it will be expensive in terms of cost I. On the other hand, if it is too large, the cost will be high, and the optimal size is about 4111. The method of dividing this by cutting with a laser or a blade is the most advantageous in terms of cost. Since the single crystal shape is uniform, the two parallel bottom surfaces of the small single crystals that are divided during processing can all be aligned to a specific crystal plane (110).

As shown in Figure 5, the (110) planes of the upper and lower end surfaces are rectangular, and the crystal orientation is <1, which is relatively easy to wear in the major axis direction.
00>, and the crystal orientation <
110 > is taken. The dimensions of this rectangle are: major axis / minor axis =
A range of 1.07 to 1.5 is appropriate; the lower limit of 1°07 is cheap in terms of cost, but little improvement in performance can be expected, and the upper limit of 1.5 is on the contrary, even if it is higher than this, there is no wedge effect. This is because the cost is also high.

It should be noted that the facial image may have a shape with the four corners rounded as long as the shape satisfies the above-mentioned major axis and minor axis.

When a die hole is drilled perpendicularly to the center of the above-mentioned appropriate rectangle, the thickness of the diamond will be relatively large on the long diameter side, and on the contrary, the thickness of the diamond will be relatively small on the short diameter side. This difference in wall thickness affects the clamping pressure during mounting during die processing, and the stress and displacement caused by internal pressure during wire drawing. In this case, it is most appropriate to use calculations based on the axially symmetric finite element method for comparative studies. As shown in the calculation results in Example 1, as the thickness of the diamond increases, the stress generated due to the internal pressure of the die tends to decrease. In particular, the stress generated near the inner surface of the die is closely related to the wear mechanism on the inner wall surface of the die, and it is considered that the lower the generated stress is, the more effective it is in reducing the wear caused by the die wall pressure.

Therefore, by making the radius of the diamond, that is, the wall thickness, on the side that is more likely to wear due to the crystal orientation of the diamond relatively large, the wear can be made to be the same as the side that is less likely to wear due to the crystal orientation, and uneven wear can be minimized as much as possible. It can be prevented.

[Example 1] As shown in Fig. 5, the upper and lower surfaces of a small single crystal divided from a diamond single crystal synthesized under ultra-high pressure and high temperature are rectangular, and the dimensions are such that the short axis radius is 0.7 mm. and the major axis radius is 0
．． 8m and 1. The following two conditions will be considered for the case where Q++m and the thickness are 1.1 fl in each case.

One is that a sintered mount is applied before a die hole is drilled perpendicular to the center of the rectangle, and the tightening is done when pressure (external pressure) is applied from the periphery to the diamond part.
The stress and displacement generated when a die hole was drilled and internal pressure was applied to the diamond part during wire drawing were calculated using the axially symmetric finite element method. When calculating, the 6th
7 and 7 respectively show the model set during sintering mounting and the wire drawing die for a rectangular synthetic diamond single crystal. In addition, in the calculation, the external pressure Q = 110 at the time of sintering mounting
kg/x*” and the internal pressure of the wire drawing die P = 220 kg/
The circumferential stress σ kg 7 m 2 and the radial displacement Ur (m) at the thickness direction Z-0, 35 mm line were analyzed for the thickness direction Z-0. The results are shown in FIGS. 8 and 9.

Note that the area below the O line in each figure is the compressive stress at the time of mounting (
Figure 8) and displacement (Figure 9).

In the figure, r1 indicates the radius of the short axis of the rectangle, and r2 and r3 indicate the radius of the long axis of the rectangle.

First, in sintered mounts, compressive stress and displacement tend to increase as the diamond radius increases, but the difference is not very large. During wire drawing dies, stress and displacement tend to decrease as the diamond radius increases. In both cases, the maximum value is shown near the die hole. In fact, the stress and displacement during wire drawing are a composite stress of the stress value during sintering mount and the stress during wire drawing internal pressure, so they tend to be similar to the stress during wire drawing internal pressure.

[Example 2] A small single crystal of a synthetic diamond single crystal is a hexahedron, and its upper and lower two faces are rectangular with crystal planes (110), and the long axis side or crystal orientation is <100>, and the single crystal is a hexahedron. Two types with orientation <110>, (A) 1° 41m x 1
, 6 inches, (B) 1.4 m x 1.8 tm, each with a thickness of 1.1 fl.

Also, as a comparison product, the upper and lower two surfaces are crystal planes (110).
I made a square 1.4 tm x 1.4 v+* with a thickness of 1.11. A die hole is perpendicular to the upper and lower sides of these hexahedral single crystals, with a diameter of 0.241 m and a diameter of 0.2 m.
A die with a diameter of 15 x m and a diameter of 0.197 tm was manufactured. In addition, we also manufactured the above-mentioned natural diamond dice for comparison.

When wet wire drawing of stainless steel MA wire 5US304 was performed using these dies under the same conditions, the amount of wire drawn until the life of the die was reached was as shown in Table 1.

That is, the product of the present invention has 1.
The performance was 0.7 to 1.75 times higher, and the performance was 1.91 to 2.91 times higher than that of the comparative natural diamond.

Table 1 Example using stainless steel 1iUS304 [Effects] As described above, the tool of the present invention uses a small single crystal of fragmented synthetic diamond to form two parallel crystal planes (110 ), the crystal plane is rectangular, and the major axis is set in the crystal orientation <10 that is easy to wear.
0> side, the crystal orientation <110 that makes it difficult to wear out its short axis
By setting it to the > side, the thickness of the diamond that penetrated the large tool changed. As a result, the crystal planes that natural diamonds and synthetic diamonds have,
For uneven wear of through-hole tools due to hardness due to crystal orientation and anisotropy of wear, by forming the synthetic diamond single crystal into the above-mentioned rectangular shape, the stress generated by internal pressure is relatively reduced when the diamond wall is thicker. Therefore, it is possible to reduce wear on the inner wall surface of the die, prevent uneven wear, and further improve performance.

[Brief explanation of the drawing]

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)
) is a front view, and FIG. 3 is an explanatory diagram of the hardness of Diamond I/crystal surface and the anisotropy of wear. The long direction of the arrow indicates that wear is easy, and the short direction indicates that wear is difficult. I~■ in Figure 4
The figure is an explanatory diagram showing the wear tendency of the die hole perpendicular to the diamond crystal plane, and [ ] indicates the crystal orientation. Fifth
Figure (a) is a plan view of a synthetic diamond single crystal with rectangular upper and lower sides, (b) is a front view, Figure 6 is a cross-sectional view of a model of a sintered synthetic diamond mount, and Figure 7 is a synthetic diamond. Figure 8 is a graph of the analysis results of circumferential stress, and Figure 9 is a graph of the analysis results of radial displacement. 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) Written by Y. May 12, 1986

Claims (1)

[Claims] 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 the two parallel end faces are rectangular, and the long axis direction is easily worn. The crystal orientation is <100>, and the short axis direction is divided into crystal orientation <110>, which is difficult to wear.
A tool using a synthetic diamond single crystal, characterized by having a perpendicular hole in the center of the rectangular surface, and having side surfaces parallel to the central axis of the hole.