Patent Publication Number: US-2006013718-A1

Title: Wear-resistant jewelry with a polycrystalline diamond compact inlay

Description:
BACKGROUND OF THE INVENTION  
      1. Technical Field  
      The present invention relates to jewelry manufacturing and more specifically relates to a method of manufacturing wear-resistant jewelry with a polycrystalline diamond compact inlay.  
      2. Background Art  
      The manufacturing process for creating jewelry has evolved over the years as new materials and methods of manufacturing have been developed and introduced into the industry. For example, while much of today&#39;s jewelry is manufactured using wear-prone precious metals such as platinum, gold, silver, and the like, various methods have been developed and implemented to employ virtually wear resistant materials, such as tungsten carbide and other advanced ceramics or sinterable materials, in jewelry manufacturing. Generally, cavities or openings are formed within the wear resistant material that forms the body of the jewelry and these cavities are subsequently filled with a precious metal. The combination of the wear resistant material and the precious metal enables the jewelry to provide both monetary value and enduring luster.  
      Another manufacturing process that has been gaining favor in various industries is the use of polycrystalline diamond compact for industrial applications, including coatings for bits, blades, and the like. This technology has proven to have practical applications in areas ranging from drilling to medical prosthesis. The use of polycrystalline diamond compacts in practical applications typically requires a fairly strong bond between the polycrystalline diamond compact and the adjacent substrate. While fairly strong, the bond formed between the diamond compact and the substrate is interstitial in nature and dependent in large part on the strength of the underlying material. The processes whereby these bonds are formed are, generally, of greatest consequence in the design and manufacture of applications employing a polycrystalline diamond compact. Many variations of these various bonding processes, or procedures, exist and are well known to those skilled in the art.  
      In general, the manufacturing of wear-resistant material and polycrystalline diamond compact both employ a process known as “sintering.” Sintering, the fundamental manufacturing process step for most porous metal products typically means the bonding of powder particles through diffusion at temperatures well below the melting point of the metal. In a given micron range, after the sintering process, no physical limits exist between the original powder particles. Sintering generally gives a porous metal material additional shape-stability and the physical properties of a metallically stronger component. Typically, the sintering process includes the use of a binder metal, generally cobalt and/or nickel.  
      In preparation for sintering, the base materials are most often held together with an organic binder and can be formed to the desired shape. After the preliminary forming has taken place, the amalgam is placed in a furnace where it undergoes the sintering process, during which the amalgamation volumetrically shrinks approximately 30%-50%. This shrinkage should most preferably be accounted for when determining the final product dimensions.  
      While the various processes described herein are not without merit and application in certain manufacturing environments, they are typically employed in very different industries and used to accomplish very disparate purposes. Accordingly, it may be desirable to combine the two aforementioned technologies to yield jewelry that economically incorporates the allure of diamond-like materials with the durability of a wear-resistant material.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention comprises a series of steps wherein a powdered material such as powdered diamond is used to form durable and attractive wear-resistant jewelry. A wear-resistant metal jewelry blank is scored or otherwise processed to create one or more grooves, voids, or openings. The voids in the jewelry blank are subsequently filled with a powdered substance. Then, the jewelry blank is heated under pressure at a temperature above the melting point of the powdered substance, but below the melting point of the metal jewelry blank, thereby forming a series of interstitial matrices. The resulting jewelry blank, with the embedded compact material, is then shaped through processes such as cutting, grinding, or the like, to the desired dimensions and polished to create one or more pieces of wear-resistant jewelry. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The preferred embodiments of the present invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and:  
       FIG. 1  is a perspective view of a jewelry blank for manufacturing wear-resistant jewelry in accordance with a preferred embodiment of the present invention;  
       FIG. 2  is a perspective view of the jewelry blank of  FIG. 1 , after creating a series of voids, in accordance with a preferred embodiment of the present invention;  
       FIG. 3  is a perspective view of the jewelry blank of  FIG. 2 , after filling the voids with a powdered diamond substance, in accordance with a preferred embodiment of the present invention;  
       FIG. 4  is a schematic representation of the jewelry blank of  FIG. 3 , housed within a pyrophyllite cell and prepared for sintering in accordance with a preferred embodiment of the present invention.  
       FIG. 5  is a perspective view of the jewelry blank of  FIG. 3 , after sintering and after separation of individual multiple jewelry pieces, in accordance with a preferred embodiment of the present invention;  
       FIG. 6  is a flow chart for a method of manufacturing wear-resistant jewelry in accordance with a preferred embodiment of the present invention; and  
       FIGS. 7, 8 ,  9 ,  10  and  11  are alternative examples of wear-resistant jewelry manufactured in accordance with a preferred embodiment of the present invention. 
    
    
      It is important to note that the exemplary figures used to describe the present invention do not limit, or constrain, the method of application or embodiment of the present invention; they merely represent possible embodiments of the present invention.  
     DETAILED DESCRIPTION  
      The preferred embodiments of the present invention comprise a series of steps wherein a powdered diamond is used to form durable and attractive wear-resistant jewelry. A wear-resistant metal jewelry blank is scored or otherwise processed to create one or more voids or opening. The voids in the jewelry blank are subsequently filled with a powdered diamond substance. Then, the jewelry blank is heated under pressure at a temperature above the melting point of the powdered diamond substance, but below the melting point of the metal jewelry blank, thereby forming a series of diamond-diamond and diamond-substrate interstitial matrices. The resulting jewelry blank, with the embedded diamond compact, is then shaped through processes such as cutting, grinding, or the like, to the desired dimensions and polished to create one or more pieces of wear-resistant jewelry.  
      Referring now to  FIG. 1 , a jewelry blank  100  used for creating wear-resistant jewelry in accordance with a preferred embodiment of the present invention is depicted. The most preferred embodiments of the present invention contemplate the use of a tungsten carbide material for jewelry blank  100 . The most preferred composition for the tungsten carbide material comprising jewelry blank  100  is tungsten carbide combined with one or more binder metals. Suitable material for jewelry blank  100  can be obtained from General Carbide and is known by the nomenclature GC-129 or the like. The chemical composition (by weight) of GC-129 is 86% WC, 10%, Ni, 2% Co, and 2% Cr 3 C 2 .  
      The outer diameter of jewelry blank  100  is most preferably slightly larger than the finish outside diameter of the jewelry piece, so as to allow for additional material removal and surface finishing while ensuring that the product dimensions lie within the desired final product specifications. Jewelry blank  100  may be ground to the desired dimensions using any technique known to those skilled in the art, including a centerless grinder, for example.  
      Referring now to  FIG. 2 , jewelry blank  100  of  FIG. 1  has been processed to create a series of grooves or trenches  210  in the surface of jewelry blank  100 . While depicted herein as a series of grooves or trenches, those skilled in the art will recognize that grooves or trenches  210  are merely representative of the type of apertures, voids or openings that may be formed. For example, diagonal and/or concordant slits may be formed in jewelry blank  100 . Similarly, in addition to grooves or trenches  210 , spherical or oval apertures or openings can be created in jewelry blank  100  by using techniques such as electrical discharge machining (EDM or wire EDM). The use of EDM processes is well known to those skilled in the art. The actual type, shape, and number of voids or openings is limited only by the imagination of the jewelry designer. Grooves or trenches  210 , as well as other types of openings, may be suitably formed in the surface of jewelry blank  100  by using any method known to those skilled in the art. This would include hand-held grinders, diamond-grinding wheels, lathes, drills, etc. in addition to the EDM techniques previously mentioned.  
      Referring now to  FIG. 3 , grooves or trenches  210  have been filled with a powdered substance  310 . Although the present illustrative example employs powdered diamond, other powdered substances may also be suitably employed. Powdered diamond substance  310  may be natural or synthetic diamond particles, most preferably in the range of 1 micron-1,000 microns in diameter. The most preferred depth of grooves or trenches  210  is in the range of 0.020 inch and 0.040 inch, so as to contain a sufficient mass of powdered diamond substance  310  to provide the desired appearance, and yet, maintain enough distance from the final product inner diameter to ensure that groove or trench  210  is not cut too deeply into the surface of jewelry blank  210  and does not penetrate completely through jewelry blank  100 . In the most preferred embodiments of the present invention, it is desirable to etch a name, or other desired inscription, on the interior of the final jewelry piece to be constructed from jewelry blank  100 . Additionally, a solvent-catalyst sintering aid (not shown this FIG.) has been placed around jewelry blank  100  to aid in the initial sintering process. Those skilled in the art will recognize that other wear-resistant materials may be used in place of powdered diamond substance  310 . These alternative materials include cubic boron nitride (CBN), ruby, etc.  
      Referring now to  FIG. 4 , an assembly  400  for manufacturing wear-resistant jewelry in accordance with a preferred embodiment of the present invention is depicted. In accordance with the preferred embodiments of the present invention, upon forming the outer surface of tungsten carbide blank  100  to the desired shape and filling grooves  210  with powdered diamond material  310  as shown in  FIG. 2  and  FIG. 3 , jewelry blank  100  is then housed in a refractory metal cylinder  420 , most preferably composed of molybdenum or zirconium. The wrapped materials are contained within a heater-sample tube  430  that is generally composed of graphite or tantalum. Heater-sample tube  430  is, in turn, packed within a pressure medium  440 , most preferably consisting of boron nitride powder. Heater-sample tube  430  is surrounded by salt cylinder  450 .  
      Current disks  460 , approximately 0.005 inches thick and most preferably composed of titanium, molybdenum, or a similar refractory metal, are placed on either end of salt cylinder  450 . Current rings  470 , most preferably composed of steel, are located on the outer edge of the outer surface of current disks  460 . Pyrophyllite buttons  490 , also known as a thermal insulation plugs, are positioned within steel rings  470 . Finally, the various components are placed within a pyrophyllite cell  480  and assembly  400  is placed in a high pressure, high temperature (HP/HT) press and subjected to sufficient temperature and pressure for a sufficient period of time to cause the powdered diamond material to form a diamond compact.  
      The HP/HT press will typically include a series of “anvils” used to hold assembly  400  in the desired position within the HP/HT press. When the anvils of the HP/HT press are in the retracted position, assembly  400  can be centered in the HP/HT press. As the anvils are closed on assembly  400 , current rings  470  will make contact with the anvils. The electrical current used to heat assembly  400  will pass through the anvils to current rings  470 . The HP/HT press, is most preferably hydraulically operated, and will be pressurized such that assembly  400  experiences the desired pressure.  
      According to the most preferred embodiments of the present invention, assembly  400  is placed in a HP/HT press at a pressure above 60 kbar and a temperature above 1500° C. for approximately 15 minutes, or until the sintering process is complete. Once assembly  400  is pressurized, a heating current is applied. The applied current will be set for a current flow of approximately 800 A, or some other appropriate value as determined by those skilled in the art. In the most preferred embodiment of the present invention, as the temperature in the assembly  400  increases beyond 1500° C., the solvent-catalyst is liquefied and powdered diamond material  310  are then dissolved in the solvent-catalyst.  
      After an appropriate period of time, depending on the material used and the shape of the jewelry blank, assembly  400  is allowed to cool to room temperature; and as assembly  400  cools, powdered diamond material  310  crystallizes to form a network composed of diamond-diamond and diamond-substrate bonds. The solvent-catalyst can be removed by leaching or other appropriate process known to those skilled in the art. In some preferred embodiments of the present invention, jewelry blank  100  may be subjected to multiple repetitive heat/pressure cycles. Additionally, those skilled in the art will recognize that the specific temperatures, pressures, times, etc. may vary, based on the specific materials used in the sintering process. The illustrative examples contained herein are provided as representative values only and may be modified by those skilled in the art to practice the invention and thereby achieve the purposes explained herein.  
      After heating and pressure have been applied to create the diamond-diamond and diamond-substrate bonds, jewelry blank  100  is removed from the HP/HT press and will generally require some outer surface finishing. According to the most preferred embodiments of the present invention, jewelry blank  100  will be ground to the desired finish outer diameter of the desired jewelry piece or pieces. At this point, jewelry blank  100  will consist of a singular piece of jewelry or a plurality of similar jewelry pieces, connected to each other.  
      The process of using an HP/HT press to create a diamond compact as described herein is merely illustrative of one process that may be suitably employed in the various preferred embodiments of the present invention and is not meant to be exhaustive or limiting in any way. The generalized use of HP/HT presses in the diamond manufacturing process is well known to those skilled in the art, and, as a matter of reference, is comprehensively discussed in U.S. Pat. No. 5,127,923 issued to Bunting et al., which patent is incorporated herein by reference. Other, similar techniques used to create natural and synthetic diamond compacts known to those skilled in the art may also be employed in the various preferred embodiments of the present invention. Additionally, as previously explained, other suitable materials such as ruby and cubic boron nitride may also be used in place of powdered diamond material.  
      In accordance with the most preferred embodiments of the present invention, the next step in the process involves the removal of the core from jewelry blank  100 . Preferably, this is accomplished through the use of wire EDM. However, a starter hole through the core may be required prior to the application of wire EDM. To perform this preliminary operation, an EDM hole drill may be employed to penetrate through the core of jewelry blank  100 . As a matter of preference, the hole will be drilled as straight as possible and located near to but closer to the center than the final inner surface of the jewelry piece. If jewelry blank  100  consists of two or more flat surfaces, the flat surfaces may be ground square, so as to facilitate squareness of the individual jewelry pieces.  
      After a small hole preferably ranging from, but not constrained to, 0.30-mm to 3.0-mm has been drilled through the solid cylinder of jewelry blank  100 , wire EDM will be used to remove additional material from the core of jewelry blank  100 , such that the inner diameter of jewelry blank  100  is slightly smaller than the diameter of the inner surface of the individual jewelry piece or pieces.  
      After removing the core of jewelry blank  100 , a lathe equipped with diamond plated mandrills may be employed to grind the remaining material on the inner surface of the now hollow cylindrical jewelry blank  100  to the desired inner surface diameter of the jewelry piece or pieces. It should be noted that there are a variety of machines that may perform this operation. Following this operation the now hollow cylindrical jewelry blank  100  may be sectioned into individual jewelry pieces if it not done so previously. The separation of jewelry blank  100  into individual jewelry pieces is depicted in  FIG. 5 . While jewelry blank  100  is shown in  FIG. 5  as being sectioned into eight separate rings, those skilled in the art will appreciate that this is merely illustrative of the process and that a single piece may be manufactured by this process as well as the multiple pieces as depicted in  FIG. 5 .  
      After jewelry blank  100  has been sectioned and the final inner and outer surfaces have been exposed, a cylindrical grinder, or similar grinder, may be used to grind the individual jewelry piece to the final product specifications. This operation may also include the shaping of the desired jewelry contours, curves, and the like. Finally, each finished jewelry piece may be polished using a diamond-polishing compound to achieve the desired final product, in accordance with the product specifications. Other supplementary finishing operations for smoothing, shaping, and polishing wear-resistant metals that may be deemed necessary to enhance the final product are well known to those skilled in the art.  
      It is important to note that the various preferred embodiments of the present invention may be used to manufacture individual jewelry pieces or in multiple quantities depending on the maximum allowable size of the jewelry that the machinery may produce and the desired squareness of the jewelry piece.  
      Referring now to  FIG. 6 , a flow chart for a generalized method  600  of manufacturing wear-resistant jewelry in accordance with a preferred embodiment of the present invention is depicted. As shown in  FIG. 6 , one or more openings are created in a jewelry blank (step  610 ). Then, the openings are filled with a powdered substance, typically powdered diamond, (step  620 ) and the jewelry blank is placed into a vacuum oven where it is subjected to high temperatures and “baked” to remove undesirable impurities that may have been introduced in the earlier process steps.  
      Next, the jewelry blank is placed in a HP/HT press where it is process to solidify the powdered substance into a solid material (compact) that is bonded to the jewelry blank (step  640 ). Once placed in the press, pressure and temperature are applied to sinter the particles and to bond the powdered materials to the jewelry blank (step  650 ). Then, the jewelry blank is removed from the HP/HT press (step  660 ) and the jewelry blank is then processed to create one or more individual jewelry pieces (step  670 ).  
      Aside from the methods whereby the subject jewelry piece is manufactured, the present invention encompasses an assortment of embodiments. In the most preferred embodiment of the present invention, as shown in  FIG. 5 , the present invention is employed to create a finished piece of jewelry shaped as a ring, suitable to be worn on a person&#39;s finger. Other preferred embodiments of the present invention may include the creation of earrings, pendants, or the like.  
      Referring now to  FIGS. 7-10 , various alternative preferred embodiments of finished jewelry pieces produced by the methods of the present invention are illustrated. The darker areas represent the embedded compact material formed by the sintering process.  
      Referring now to  FIG. 11 , the final width of the jewelry blank of wear-resistant material has been achieved by removing wear-resistant material sections  1110  from the sides of the finished jewelry piece. In this instance, the entire visible surface of the finished jewelry piece is now comprised of the compact material. In this specific embodiment, the inner surface of the finished jewelry piece is comprised of the wear-resistant material and the compact material is no longer embedded, but appears as a surface coating on the finished jewelry piece.  
      From the foregoing description, it should be appreciated that wear-resistant jewelry incorporating a polycrystalline diamond compact and a method for producing a wear-resistant jewelry piece incorporating a polycrystalline diamond compact is provided and present significant benefits that would be apparent to one skilled in the art. Furthermore, it should be appreciated that a vast number of variations in the embodiments exist. Lastly, it should be appreciated that these embodiments are preferred exemplary embodiments only, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description provides those skilled in the art with a convenient framework for implementing various preferred exemplary embodiment of the present invention. It should also be noted that various changes may be made in the function and arrangement of elements described in the exemplary preferred embodiment without departing from the spirit and scope of the invention as set forth in the appended claims.