FR2728487A1 - DIAMOND DRAWING LINE - Google Patents

Abstract

A die blank has a CVD diamond body (10) having a hole (14) that extends through. The blank is characterized by the orientation (20) of the diamond crystals which is mainly radial. The blank can be manufactured by depositing a layer of diamond by chemical gas deposition on a metal wire and removing the wire to produce a CVD diamond sheath.

Description

This invention relates to dies.

  The dies have a hard material core mounted in a relatively solid support and having an axially formed hole. The wire is pulled through the hole, which causes the wire to decrease in diameter. Examples of hard materials that have been used for the central core of the dies are cemented carbides, compacted diamonds and CVD diamond, that is, diamond made by chemical deposition.

gas phase.

  Diamond is the hardest substance known to man and can be found in nature or produced synthetically. A synthetic diamond manufacturing process is chemical vapor deposition (CVD). Diamond produced by chemical vapor deposition is known as CVD diamond. The CVD diamond can be manufactured by providing a gaseous carbon compound such as a hydrocarbon, by subjecting the gaseous carbon compound to energy such as microwave energy to dissociate the compound into carbon-containing ions, atoms, or radicals. in the presence of an activating gas such as hydrogen, and allowing carbon-containing ions, atoms or radicals to deposit on a suitable substrate and form a diamond layer. These processes are well

  documented in the literature, including patents.

  U.S. Patent No. 5,361,621 discloses a CVD diamond die which has smaller diamond grits adjacent to an initial diamond growth surface with larger diamond grits adjacent to an opposing surface, with an opening having a substantially circular section wire support portion which determines the diameter of the wire and is positioned closer to the initial growth surface in a smaller grain area than the coarse final opposed surface. A preferred orientation of the diamond crystals is that in which the diamond crystals have a parallel, or substantially parallel, orientation to the opening or hole through the die. A similar CVD diamond die is

  described in United States Patent 5,363,687.

  U.S. Patent No. 5,377,522 discloses another CVD diamond die which has a body having an upper surface and a lower surface and an opening or hole that extends through the body from the top surface to the lower surface. A preferred orientation of the diamond crystals is that in which the diamond crystals have an orientation <110> perpendicular to the axial direction of the aperture. The industry is

  made from a polycrystalline diamond film.

  The die produced from such a film has a diamond crystal orientation shown diagrammatically in Figure 3 of the accompanying drawings, i.e. a few diamond crystals have a radial orientation with respect to the aperture, but the majority of diamond crystals has an orientation that is not radial but parallel or essentially

  parallel to the diameter of the die.

  According to the present invention, a die blank comprises a CVD diamond body having a substantially circular cross-sectional hole which extends through, the predominant orientation of the diamond crystals in the body being radial to the hole. A die can be made from this blank by surrounding the blank with a relatively massive support to which it is attached. Such a

  die also forms one aspect of the invention.

  According to another aspect of the invention, a method of manufacturing a die blank as described above comprises producing a diamond layer by chemical vapor deposition on a wire or non-metallic filament and removing the wire or filament to produce a CVD diamond sheath. FIG. 1 is a longitudinal section of one embodiment of a CVD diamond die blank of the invention; FIG. 2 is an end view of the blank of FIG. 1; FIG. Figure 4 is a perspective view of a wire having a CVD diamond layer grown thereon, FIG. 4 is a perspective view of a wire having a CVD diamond layer grown thereon, FIG. 5 is a sectional view of a base having a plurality of wires extending therefrom and on which a layer of CVD diamond has been deposited, and FIG. 6 is a top view of the

figure 5.

  In the sector of the invention, the dominant orientation of the diamond crystals in the body is radial with respect to the hole which extends through and

  therefore perpendicular to the direction of traction of the wire.

  Preferably, the orientation of the diamond in the radial direction is <110> or <111> or a combination thereof in order to provide the diamond core with optimum hardness and wear resistance at the surface. o this is the most important, that is, the one that is in contact with the wire. Such a predominant orientation of diamond crystals is not found in prior art CVD diamond die blanks and provides the die of the invention with improved hardness and wear resistance as well as a smaller amount of grains (particles)

  than in the sectors of the state of the art.

  Preferably at least 50%, more preferably at least 75%, and even more preferably at least 90% of the orientation of the diamond crystals in the body is

radial to the hole.

  The die blank generally has a cylindrical shape which in plan can be circular, triangular, hexagonal, square or

rectangular.

  The blank of die of the invention can be surrounded by a relatively massive support and fixed to this support to produce a die. The blank may be attached to the support by soldering, mechanically, or a combination thereof. These attachment methods are known in the state of the art. The relatively massive support is typically manufactured in

  cemented carbide, steel or equivalent.

  The die blank of the invention is made by depositing or fabricating a diamond layer by chemical vapor deposition on a wire or a nonmetallic filament and then removing the wire or filament to produce a coating. CVD diamond. The deposited layer extends well

  obviously totally around the wire or filament.

  The CVD diamond sheath, particularly if the wire or filament on which the CVD diamond layer is deposited is relatively long, can be cut, for example cut, at one or more points along its length to produce two sheaths, or rings, smaller, or even more, each of them

  constituting a draft of die.

  The wire is typically selected from the transition metal wires. An example

  a particularly suitable metal is tungsten.

  The non-metallic filament is of those

  can allow CVD diamond growth on it.

  An example of such a suitable filament is a filament

silicon carbide.

  Several CVD diamond sheaths can be made by providing several spaced wires or filaments that extend beyond a surface of a base, by depositing a layer of CVD diamond on each wire or filament to provide a diamond deposit CVD, removing strands or filaments coated from the base and removing strands or filaments to produce several CVD diamond sheaths. The yarns or filaments may be made of the same material as the base or in a different material such as

that described above.

  The yarns or filaments can be removed from the CVD layers deposited thereon by methods known in the state of the art such as acid etching. Embodiments of the invention will now be described with reference to the accompanying drawings. Referring firstly to FIGS. 1 and 2, there is shown respectively a longitudinal section of a blank of a CVD diamond die.

  of the invention and an end view thereof.

  The blank comprises a straight circular cylindrical body 10 having an outer circular peripheral surface 12 and a centrally disposed hole 14 which extends across a flat surface 16

  to an opposite flat surface 18.

  The body 10 is composed of CVD diamond having the orientation of diamond crystals 20 (shown schematically) predominantly radial with respect to the circular hole 14. The orientation of the diamond crystals 20 is preferably the <110> orientation or <111> or a combination thereof. It can thus be seen that the predominant orientation of the diamond crystals is perpendicular to the direction of tension of the wire, which provides the blank with excellent hardness and excellent abrasion and wear resistance and tearing of the wire. weaker grain. The orientation of the diamond crystals of the die blank of the invention is the opposite of what is produced by following the teachings of the invention.

  U.S. Patent 5,377,522 described above.

  The die blank of this US patent is produced from a polycrystalline diamond wire shown in Figure 2 of the patent in question. Such die blank has a diamond crystal orientation shown schematically in Figure 3 of the accompanying drawings. This blank die 22 is also of straight circular cylindrical shape and has an outer surface 24 and a circular hole disposed

  centrally 26 which extends through.

  The orientation of the diamond crystals 28 is shown schematically. It should be noted that part of the orientation of the diamond crystals 28 is radial with respect to the hole 26, but that the predominant orientation is parallel, or essentially

  parallel to the diameter of the blank.

  A die can be made from the blank described above and illustrated in FIGS. 1 and 2 by fixing, for example by brazing, mechanically or a combination thereof, the surface

  12 outside on a relatively massive support.

  The die blank of the invention may be manufactured according to the method which will now be described with reference to FIG. 4. Referring to this figure, a wire 30, such as a tungsten wire, is provided and a layer 32 of CVD diamond is brought to croltre above by methods known from the state of the art. The CVD diamond layer extends completely around the wire. The layer 32 symmetrically increases on the wire giving it a uniform thickness. The yarn can then be removed, for example by acid etching, leaving a CVD diamond sheath having a hole extending therethrough. This sheath can constitute the blank of die. Alternatively, if dies having a smaller depth, i.e. a distance between the lower surfaces 16 and 18, are desired, the sheath can then be cut, for example by cutting or etching, along its length. in one or more points to produce several smaller sleeves or rings, which

  each constitute a draft of a sector.

  A possible advantage of the process of the invention is that the hole in the die blank is produced at the source and must not be formed by

the end user.

  Several CVD diamond sheaths may be manufactured according to a method which will now be described with reference to FIGS. 5 and 6. Referring to these figures, a base 40, made of a material such as molybdenum, is provided and presents a

  lower surface 42 and an upper surface 44.

  Several spaced tungsten wires 46 are in the base 40 and extend from the surface 44. A layer 48 of CVD diamond is deposited on the surface 44 and on each individual wire to provide each wire with a CVD diamond coating. , as illustrated. The coated yarns are then removed, for example by cutting or etching along the dashed line 52, and chemically cut or etched again along the dashed line 54 to produce a plurality of CVD coated diamond yarns as illustrated in FIG. Figure 4. The wires can be removed to produce CVD diamond sheaths and the sheaths are optionally cut, as described above. In a variant of the embodiment of FIGS. 5 and 6, the wires 46 may be made of the same material as the base 40. They may then be formed for example by eroding a base by electro-erosion in order to provide a surface of the base a profile with teeth. Teeth are part

  integral of the base and replace the wires 46.

Claims (16)

  1. Die blank, characterized in that it comprises a CVD diamond body (10) having a hole (14) of substantially circular cross section which extends through, the predominant orientation (20) of the diamond crystals in the body (10) being radial relative to the hole (14).   2. Die blank according to claim 1, characterized in that at least 50% of the orientation (20) of the diamond crystals is radial with respect to hole (14).   3. Die blank according to claim 1, characterized in that at least 75% of the orientation (20) of the diamond crystals is radial with respect to hole (14).   4. Die blank according to claim 1, characterized in that at least 90% of the orientation (20) of the diamond crystals is radial with respect to hole (14).   5. Die roughing according to any one of   preceding claims, characterized in that   the orientation (20) of the diamond crystals is the <110> or <111> orientation or a combination thereof. 6. Roughing die according to any one of   preceding claims, characterized in that the   body (10) is cylindrical in shape.   7. Die blank according to claim 6, characterized in that the shape of the body (10), in plan, is circular, triangular, hexagonal, square or rectangular. 8. Die, characterized in that it comprises   a blank according to any one of the claims   previous surrounded by a relatively massive support to which it is fixed.   9. Die according to claim 8, characterized in that the relatively solid support is manufactured from cemented carbide, steel or equivalent.   10. Die according to claim 8 or claim 9, characterized in that the blank is fixed to the support by brazing, mechanically or a combination of these.   11. A method of manufacturing a blank   die according to any one of claims 1 to   7, characterized in that it comprises producing a diamond layer (32, 48) by chemical vapor deposition on a wire or a non-metallic filament (30, 46) and removing the wire or filament in order to produce a CVD diamond sheath.   12. The method of claim 11, characterized in that the sheath is cut at one or more points along its length to produce two smaller sheaths or more.   13. The method of claim 11 or 12, characterized in that the layer (32, 48) CVD diamond is manufactured on a wire (30, 46) selected   among the transition metal wires.   14. The method of claim 13, characterized in that the metal is tungsten. 15. Process according to any one of   Claims 11 to 14, characterized in that several   spaced wires or filaments (46) are provided to extend beyond a surface (44) of a base (40), a layer (48) of CVD diamond is deposited on each wire or filament (46) in order to produce a CVD diamond deposit thereon, the coated threads or filaments are removed from the base (40) and the threads or filaments are removed to produce a plurality of CVD diamond sheaths. 16. The method of claim 15, characterized in that the son or filaments are removed from the base by cutting.