Method of Working Gemstones

Abstract

The invention provides a method of gemstones working enabling rapid gemstone working member exchange and gemstone processing sequence continuation without the need to level the gemstone or the working member. The invention also provides a rotatable support having an axis of rotation and a registering feature. The registering feature precisely positions and aligns an interchangeable abrading article so that its working surface rotates in a predetermined plane, which has fixed position relative to the gemstone.

Description

FIELD OF THE INVENTION

The present invention relates to the field of gemstone working and in particular, to a method of gemstone working enabling rapid gemstone working member exchange and gemstone processing sequence continuation without the need to level the gemstone or the working member.

BACKGROUND OF THE INVENTION

Grinding and polishing are the most common gemstone working (shaping) operations. Gemstones can be polished or worked in different ways. Most commonly, gemstones are polished or worked mechanically on a fast rotating metal working member or scaife. A scaife is a heavy, cast iron, horizontally spinning wheel with a working surface impregnated with oil and diamond powder.

To obtain the maximum gem brilliance, the facets must be the right size, have correct angles to each other, and their surfaces must be finely polished with irregularities not larger than a few nanometers. For gemstone working purposes, the gemstone is mounted on a dop held by a tang and it is leveled with respect to the working member. The gemstone leveling procedure provides for the correct angles and right size of the facets. The term gemstone includes diamonds, other precious and semi-precious stones.

European Patent No. 0 299 692 B1 to Blondeel teaches that for gemstone polishing, the scaife axial (vertical run out) position stability is important. Diamonds are especially sensitive to vertical run out. If the axial run out of the diamond impregnated surface of the scaife exceeds ±0.005 mm the polished gemstone (especially if it is a diamond) may be fractured. Blondeel uses magnetic levitation and certain predefined rotational frequencies to stabilize the scaife.

As the number of diamonds polished on the same scaife increases, the diamond impregnated surface of the scaife wears out. Sometimes grooves are formed in it and the scaife has to be renewed. For the purpose of renewal, the scaife is removed from the polishing machine and delivered for so called maintenance. The diamond impregnated surface is removed and a new surface, that possesses the same flatness as the original scaife working surface, is formed. Following formation of a new surface, the scaife has to be balanced. Handling of the scaife, which weighs 15-18 kilograms, is not an easy procedure.

Not every renewed scaife is suitable for polishing diamonds. In many cases grooves are formed on the diamond impregnated surface of the scaife. When such a scaife is sent for maintenance, the grooves are not completely removed. This practice is adopted because users do not want to waste the unused diamond impregnated part, which would be lost if the grooves were removed completely. Instead, the surface of the scaife is polished. This makes the surface smooth but does not remove some of the deeper grooves. If the remaining deeper grooves cause differences in the flatness of the renewed diamond impregnated surface exceeding ±0.005 mm, the polishing process may result in chipped culets and imperfect facets.

When a renewed or another scaife having the same or different, diamond powder grade required by the process sequence, is mounted in a diamond working machine the diamond impregnated surface is at a different height plane that the original height plane. This dictates a need for leveling of the gemstone to be polished. Without a proper leveling procedure, the polishing facet angle will be changed and the total internal reflection conditions will not exist. The brilliance of the polished gemstone will be adversely affected. The leveling operation takes time and reduces the machine throughput.

U.S. Pat. No. 5,503,592 to Neumann attempts to solve the problem of using working members having different diamond powder grades. Neumann discloses a gemstone working apparatus which includes a rotatable base, two gemstone working members including a first gemstone working member which defines a first gemstone working surface adapted for removable mounting on the base; and a second gemstone working member which defines a second gemstone working surface, of a different grain size than that of the first gemstone working surface. The second member is adapted for removable mounting on the base concentrically with the first gemstone working member and has height adjustment means that brings the second working surface into planar alignment (leveling) with the first working surface. The surface of the second member wears quicker than the surface of the first member. The second surface can however, be replaced. According to the invention this allows performing a sequence of gemstone working operations including second surface replacement in the course of polishing. The replacement however, requires realignment of the surface replaced, which is performed by adjusting the height of the surface of the second working member. Replacement of the first member is performed in a conventional way.

The surface height adjustment of the second member must be performed with micron accuracy; otherwise, the working of a diamond would be impossible. Such realignment is difficult or nearly impossible to perform since both sides of the second member are diamond impregnated and do not provide the desired planar contact between the engaging surfaces. The gap between the first and second surface is always present making this method not practical for working of diamonds and certain other fragile gemstones.

The background art does not teach or suggest a method of working a gemstone and exchanging the working member that does not require leveling of the gemstone or the working surface of the new working member. The diamond working industry would benefit if such a method would exist. The diamond industry would further benefit if hardware enabling a method of exchanging the working member that does not require leveling of the gemstone or the working surface would exist.

SUMMARY OF THE INVENTION

The present invention provides a method of working a gemstone on a gemstone working member exchange or replacement that does not require any maintenance and leveling procedures.

It is therefore an object of the present invention to provide a method of gemstone, and particularly diamond, working that enables gemstone working member exchange and gemstone processing sequence continuation without the need for leveling the gemstone or the working member.

An additional object of the present invention is to provide a working member exchange or replacement where leveling of the gemstone being worked or of the working member in the course of a gemstone processing sequence is not required.

It is a further object of the present invention to provide a gemstone working method that could be implemented on existing gemstone working machines.

An additional object of the present invention is to provide a gemstone working apparatus facilitating utilization of the gemstone working method.

According to the teaching of the present invention, the method of working a gemstone includes providing a rotatable support having an axis of rotation and a registering feature. The registering feature is operable to determine a registering plane perpendicular to the axis of rotation. The method further includes providing a fixture configuration operable to hold the gemstone at an adjustable level relative to the registering plane, and placing the gemstone to be held in the fixture configuration. The method also includes providing a plurality of interchangeable abrading articles, each of which has a working surface and each of which is operable to couple to the rotatable support.

According to a further teaching of the present invention, the method includes coupling a first abrading article of the plurality of interchangeable abrading articles to the rotatable support. The coupling is followed by leveling of the fixture configuration prior to using the first abrading article, setting the adjustable level to a working level, and working the gemstone on the working surface of the first abrading article.

In agreement with the teaching of the present invention, the method further includes; replacing the first abrading article by a second abrading article of the plurality of interchangeable abrading articles; coupling the second abrading article to the rotatable support and working the gemstone on the working surface of the second abrading article while maintaining the adjustable level at the working level, without repeating the leveling prior to using the second abrading article.

As used herein, the term “rotatable support” may be understood as a support having an axis of rotation and a “registering feature”. The term “registering feature” denotes a feature of the rotatable support, which precisely positions and aligns the abrading article so that its working surface rotates in a predetermined plane, which has a fixed position relative to the gemstone. The predetermined plane may be a “registering plane” perpendicular to the axis of rotation of the rotatable support.

In agreement with the teaching of the present invention, the registering feature is not associated with any specific hardware. The registering feature may be a combination of flat and cylindrical surfaces, a single surface such as a convex, concave or conical surface and any other arrangement that ensures precise position and alignment of the abrading article so that its working surface rotates in a predetermined plane.

According to the teaching of the present invention, the working surface of the abrading article is coated with abrasive material. The abrasive material is diamond powder. The diamond powder may be of a single grade or sections of the abrading article may be coated by different grades of diamond powder. Optionally, the working surface of each of the plurality of abrading articles may be coated by diamond powder of different grades, as may be required by a particular gemstone working sequence.

In agreement with the method of the present invention, the distance from the working surface to the registering plane is substantially identical for each of the plurality of interchangeable abrading articles when coupled to the rotatable support. According to one exemplary embodiment, the rotatable support consists of a single material. According to another embodiment, the rotatable support may consist of more than one material.

According to the method of the present invention, the interchangeable abrading article is operable to couple to the rotatable support via the registering feature.

In agreement with the method of the present invention, the working is selected from the group consisting of polishing and grinding.

The present invention provides for using the method of working a gemstone in existing conventional gemstone working machines. It also enables and promotes construction of gemstone working apparatuses characterized in that they are specially adapted for use of the method.

When the working surface of the interchangeable abrading article wears out or becomes unusable, the abrading article is simply replaced by another abrading article. Use of an interchangeable abrading article eliminates the need for working member maintenance.

Replacement of the abrading article does not change the distance from the working surface to the registering plane and does not cause the need to level the gemstone being worked or the abrading article. This shortens the time required for working a gemstone and reduces the gemstone working cost.

The rotatable support may be built in such a way that it installs on the existing gemstone working machine in a way similar to a conventional scaife. This enables application of the method of working a gemstone to existing gemstone working equipment while preserving the earlier made investments and further reducing the gemstone working costs.

The cost of the interchangeable abrading article is low when compared to conventional scaife renewal cost, allowing its disposal upon use. This simplifies material handling and further reduces gemstone working costs.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other objects, features and advantages of the invention will be apparent from the more detailed description of the exemplary embodiments of the invention, as illustrated in the accompanying drawings in which like reference numbers refer to the same parts throughout the different figures. The drawings are not necessarily to scale. Emphasis is placed upon illustrating the principles of the invention.

FIGS. 1A, 1B and 1C illustrate some elements of prior art gemstone working method;

FIGS. 2A-2D are schematic illustrations of exemplary embodiments of the hardware enabling the method of working a gemstone of the present invention;

FIG. 3 is a schematic illustration of an abrading article coupled with the rotatable support which is a part of the present invention, and

FIG. 4 is a schematic illustration of the method of working a gemstone of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

By way of general introduction, before addressing the drawings in detail, it should be appreciated that certain exemplary and non-limiting implementations of the present invention provide a method of working a gemstone. The invention also provides the hardware enabling the method of working a gemstone of the present invention.

Reference is now made to FIG. 1, which illustrates some of the elements of a prior art method of working a gemstone. FIG. 1A shows a spindle type working member or scaife 100, commercially available from NOVEX GmbH., Nuremberg, 90473 Germany and other sources. Flat scaife 112, as shown in FIG. 1C, also exists. Working member 100 is a heavy, cast iron, horizontally spinning metal wheel having a rotational axis or shaft 102; a section 104 of rotational axis 102 is adapted to engage a gemstone working machine with a source of rotational movement. Working member 100 further has a large and relatively thick disk-like section 108 the working surface 110 of which is impregnated with diamond powder.

Fixture configuration 116 involves one or more devices for holding gemstone 120 at a particular angle and height relative to working surface 110. Configuration 116 may include a dop 122 and a tang 124. Fixture configuration 116 may be a hand-held block that travels back and force in the direction indicated by arrow 130 on horizontal surface 128. Alternatively, configuration 116 may be an automatic block that moves gemstone 120 back and force on surface 128.

As the number of gemstones polished on the same working member (scaife) increases, the diamond impregnated surface 110 of the working member wears out or becomes unusable. In order to renew working surface 110, working member 100 is removed from the gemstone working machine and delivered for maintenance where diamond impregnated surface 110 is removed and a new surface 110 is formed (FIG. 1B) that possesses the same properties and flatness as the original working member surface 110. Because of the maintenance process, some of the thickness of cylindrical section 108 of working member 100 is removed and working surface 110′ operates in a different plane from the one in which working surface 110 operated. Gemstone 120 meets working surface 110′ at a different angle and height that do not correspond to the required facet angle. This dictates the need for releveling of the gemstone to be worked.

A similar need for leveling the gemstone exists when another scaife required by the gemstone working sequence having the same or different, diamond powder grade, is mounted in a diamond working machine.

The present invention provides a method of working a gemstone and particularly diamonds, enabling gemstone working member exchange and gemstone process sequence continuation without the need to level the gemstone or the working member. The term “working” in the context of the present invention includes polishing and grinding of gemstones and other precious and semi-precious stones.

According to the teaching of the present invention, the method of working a gemstone includes providing (Block 220, FIG. 4) a rotatable support 140 (FIG. 2A) having a support section 138, axis of rotation 142 and a registering feature. The term “registering feature” denotes a feature of the rotatable support, which precisely positions and aligns abrading article 160 so that its working surface 162 rotates in a predetermined plane, which has a fixed position relative to the gemstone. The predetermined plane may be a “registering plane” and the registering feature is operable to determine a registering plane 148 perpendicular to the axis of rotation of rotatable support.

The registering feature is not associated with any specific hardware. In one exemplary embodiment shown in FIG. 2A, a combination of flat surface 146 of rotatable support 140 and a cylindrical section 144 with axis of rotation 142 provide the function of the registering feature. In another exemplary embodiment (FIG. 2B) a combination of flat surface 152 of rotatable support 150 and cylindrical section 154 of protrusion 156 of support 150 provides the function of the registering feature. FIG. 2C shows a rotatable support 170 having a convex (concave) surface 172 and FIG. 2D shows a section of axis of rotation or shaft 182 having conical surface 184. Conical surface 184 may also have a key or a number of grooves engaging complementary sections of abrading article 180. Surfaces 172 and 184 may provide the function of the registering feature.

The method further includes providing a fixture configuration 116 (Block 220) operable to hold gemstone 120 at an adjustable level relative to the registering plane 148, and placing gemstone 120 into fixture configuration 116. The method also includes providing a plurality of interchangeable abrading articles 160. Each of abrading articles 160 has working surface 162 and each abrading article 160 is operable to couple with rotatable support 140. Working surface 162 of abrading article 160 is coated with abrasive material. The preferred abrasive material is diamond powder. Any method of coating by diamond powder such as impregnation, electroplating or use of adhesive materials is suitable for coating of surface 162. Further to this, working surface 162 may contain sections having different grades of diamond powder for making all gemstone working sequences on the same working surface. The working surface of each of the plurality of abrading articles may be coated by diamond powder of different grades, as may be required by a particular gemstone working sequence.

Generally, an abrading article may have different forms, although the simplest form of abrading article 160 is a disk-like article. Surface 162 is a flat surface having a high degree of flatness. Flatness of surface 162 is especially important if the abrading article rests on flat surface 146 of rotatable support 140. Typically, abrading article 160 would have a thickness of 1 mm to 6 mm. Rotatable support 140 provides the necessary stiffness keeping working surface 162 flat when working a gemstone. Abrading article 180 (FIG. 2D) has no support and should be thick enough not to wobble under the pressure of the worked gemstone.

According to a further teaching of the present invention, the method includes coupling (Block 222, FIG. 4) a first abrading article 160 of the plurality of interchangeable abrading articles to rotatable support 140 and retaining it on rotatable support 140. Different retaining mechanisms may be operable to retain the abrading article on the rotatable support. FIG. 2A shows an exemplary embodiment where permanent magnet inserts 200 distributed across rotatable support 140 retain abrading article 160, which, in this case, should be made of a ferromagnetic material. Electro-magnetic inserts may replace permanent magnet inserts 200. Alternatively, nut 158a in FIG. 2B engages thread 158b to retain abrading article 160. FIG. 2D is an illustration of a similar retaining mechanism where nut 186a engages thread 186b to retain abrading article 180. In yet another embodiment illustrated in FIG. 2C, vacuum provided by vacuum pump 178 through rotary joint 176 retains abrading article 172 on rotatable support 170.

FIG. 3 is a schematic illustration of abrading article 160 coupled with rotatable support 190. Vacuum provided by vacuum pump 178 through rotary joint 176 retains abrading article 160 on rotatable support 190.

(Block 224, FIG. 4) To set the adjustable level to a working level after the coupling operation and prior to using first abrading article 160, fixture configuration 116 is leveled. After this, working (Block 226, FIG. 4) of gemstone 120 on working surface 162 of first abrading article 160 may begin.

Generally, one abrading article 160 may be sufficient for working a number of gemstones. There may be cases where only one or more facets of a gemstone were worked on a particular abrading article and the article wears out becoming unusable or the gemstone working sequence requires an abrading article coated by different grades of diamond powder. (Block 228, FIG. 4). In agreement with the teaching of the present invention, the method further includes (Block 232, FIG. 4) replacing first abrading article 160 by a second abrading article of the plurality of interchangeable abrading articles 160; Coupling the second abrading article 160 to rotatable support 140 and working gemstone 120 on the working surface of second abrading article 160 while maintaining the adjustable level at the working level. The leveling process is not repeated prior to using the second abrading article.

In agreement with the method of the present invention, the distance from working surface 162 to registering plane 148 is substantially identical for each of the plurality of interchangeable abrading articles when coupled to rotatable support 140 and working surface 162 that may coincide with registering plane 148. In any case, the vertical run-out of the registering plane may not exceed ±0.005 mm. In order to achieve this run-out, both the abrading article and the rotatable support manufacturing should be subject to tight process control. Manufacture of the abrading article may involve repetitive grinding and thermal processing steps that provide the desired flatness, accurate dimensions and prevent any stress accumulation that may cause abrading article 160 to warp and lose flatness.

Flat surfaces 146, 152 and 192 (FIG. 3) of rotatable supports 140, 150 and 190 may consist of a homogeneous single material. This simplifies surface processing. In prior art solutions, such as U.S. Pat. No. 5,503,592 to Neumann, the magnetic ring and steel support on which the ring rests are both in direct contact with the second member surface. Since the magnetic ring and its steel support are made of two different materials, they cannot be ground to the same surface quality and level of flatness.

FIG. 2A illustrates an exemplary rotatable support 140 of the present invention having magnetic or electromagnetic inserts 200. There is no direct contact however, between permanent magnet inserts 200 and any of the surfaces of abrading article 160. Magnetic inserts 200 are inserted in troughs made in body 150 of rotatable support 140. A material layer exists between magnetic inserts 200 and the lower surface of abrading article 160. This method of insertion of permanent magnets provides a homogeneous single material structure to surface 146, which may be thus manufactured with greater accuracy and at a lower expense. Use of permanent magnets or electromagnets necessitates use of ferromagnetic material for the abrading article. For other types of retention mechanisms, the abrading article may be made of a non-magnetic material or composite material meeting the above-described manufacturing requirements.

As previously indicated, a single material structure simplifies rotatable support manufacturing and enables manufacturing rotatable supports with greater accuracy meeting the method requirements. Generally, the rotatable support may consist of more than one material. For example, vacuum orifices may be inserts and surfaces 172 (FIG. 2C) and 184 (FIG. 2D) that may have keys or inserts (not shown) made of different materials.

The present invention provides for using the method of working a gemstone in existing conventional gemstone working machines. FIG. 2A illustrates an exemplary form of rotatable support 140 having a form similar to prior art working member 100 (FIG. 1A) that includes a section 104 adapted to engage a source of rotational movement of a conventional gemstone working machine. Such form of rotatable support 140 allows for using an abrading article of the present invention with existing gemstone working machines. The exemplary form of rotatable support 140, similar to the conventional working member, was selected for demonstration purposes only. As demonstrated, other forms and shapes of the rotatable support are possible.

The present invention enables and promotes construction of gemstone working apparatuses characterized in that they are specially adapted for using the method of working gemstones of the present invention. In such an apparatus, the rotatable support is in permanently engaged with a source of rotational movement of the gemstone working apparatus and generally is not replaced or removed from the apparatus. In addition, the apparatus includes a source of rotational movement, gemstone holding, and leveling means.

The disclosed method of working a gemstone and particularly diamonds enables gemstone working member exchange and gemstone processing sequence continuation without the need to level the gemstone or the working member.

Replacement of the abrading article does not change the distance from the working surface to the registering plane, which is substantially identical for each of the plurality of interchangeable abrading articles when coupled to the rotatable support and does not cause the need to level the gemstone being worked or the working surface of the abrading article. This reduces the time required for working a gemstone and further reduces the gemstone working cost.

The abrading article, which is part of the present invention does not require maintenance. When the working surface of the abrading article wears out it is simply replaced. This eliminates the need to handle a heavy working member, its balancing and transportation and reduces gemstone-working costs.

The cost of manufacturing the interchangeable gemstone abrading article is lower than the cost of conventional working member (scaife) maintenance. Accordingly, the abrading article may be disposed upon completion of its use.

The rotatable support may be built in such a way that it installs on existing gemstone working machines in a way similar to a conventional scaife. This enables application of the method of working a gemstone to existing gemstone working equipment while preserving the earlier made investments and further reducing the gemstone working costs.

While the present invention has been described in detail, it should be understood that various changes, substitutions and alterations could be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1.-21. (canceled)

22. A replacement scaife for use in gemstone working operations, said scaife comprising: a rotatable support comprising a registering feature operable to determine a registering plane; and a disposable and replaceable abrading article coupling on one side with said support and comprising on a second side an abrading working surface, and; wherein the abrading article is coupled with the support such that it forms a scaife and the working surface rotates in a predetermined registering plane; and where replacement of the abrading plane by another abrading plane maintains the position of said working surface with respect to said registering plane.

23. The replacement according to claim 22, wherein said coupling of said support with said abrading article is performed via the registering feature.

24. The replacement according to claim 22, wherein said registering plane has a fixed position relative to a gemstone.

25. The replacement according to claim 22, wherein said working surface of said abrading article is coated with diamond powder of at least one grade.

26. A method of gemstone working said method comprising: a) providing a gemstone working machine and replacing a conventional scaife by the replacement scaife of claim 22;b) coupling at least one disposable interchangeable abrading article to said rotatable support such that said article working surface rotates in a predetermined registering plane, said plane has a fixed position relative to gemstone; c) working at least one facet and adjusting said fixture with gemstone with respect to said registering plane to set a gemstone working level and working the gemstone; d) replacing said abrading article, and wherein replacement of one abrading article of a plurality of disposable abrading articles by another does not require leveling of said gemstone or said abrading article.

27. The method according to claim 26, wherein the position of said working surface with respect to said registering plane when coupled to said rotatable support is identical for each of said plurality of abrading articles.

28. The method according to claim 26, wherein said working surface of each of said plurality of abrading articles is coated with diamond powder of at least one grade.

29. The method according to claim 26, wherein coupling of said abrading article to said rotatable support forms a device similar to the conventional scaife.

30. The method according to claim 26, wherein each of said interchangeable abrading articles is operable to couple to said rotatable support via said registering feature.

31. A method of coupling a gemstone abrading article to a rotatable support said method comprising: a) providing a plurality of interchangeable abrading articles, each of which comprises a working surface and each of which is operable to couple to a rotatable support; b) providing a rotatable support comprising a registering feature operable to determine registering plane; c) coupling at least one disposable interchangeable abrading article to said rotatable support such that said article working surface rotates in a predetermined plane being in fixed relation with said registering plane generated by said registering feature.

32. The method according to claim 31, wherein the coupling of the abrading article to the rotatable support forms a device similar to a conventional scaife.

33. The method according to claim 31, wherein the position of said working surface with respect to said registering plane when coupled to said rotatable support is identical for each of said plurality of interchangeable abrading articles.

34. The method according to claim 31, wherein said abrading articles are disposable articles.

35. The method according to claim 31 wherein said working surface of each of said plurality of abrading articles is coated with diamond powder of at least one grade.

36. The method according to claim 31, wherein each of said interchangeable abrading articles is operable to couple to said rotatable support via said registering feature.

37. The method according to claim 31, wherein said abrading article rests on flat, homogeneous single material surfaces of said rotatable support.

38. A gemstone working machine, said machine comprising: a source of rotational movement; a rotatable support for holding and rotating abrading articles and comprising a registering feature for coupling with a plurality of abrading articles, each of which comprises a working surface, such that said working surface rotates in a predetermined plane generated by said registering feature; and wherein said rotatable support is in permanent engagement with the source of rotational movement.

39. The machine according to claim 38, wherein replacement of one abrading article of said plurality of abrading articles by another maintains said working surface in said predetermined plane said plane being identical for each of said plurality of interchangeable abrading articles.

40. The machine according to claim 38, wherein said working surface of each of said plurality of abrading articles is coated with diamond powder of at least one grade.

41. The machine according to claim 38, wherein said article is a disposable article.

42. A method of gemstone working said method comprising: a) providing a conventional gemstone working machine, said machine including: i. a fixture for holding gemstone with a gemstone, and ii. a conventional scaife; b) providing a plurality of disposable interchangeable abrading articles, each of which comprises a working surface and each of which is operable to couple to a rotatable support; c) replacing said conventional scaife by a rotatable support comprising a registering feature operable to determine registering plane such that said working surface rotates in a said plane; d) coupling at least one disposable interchangeable abrading article to said rotatable support such that said article working surface rotates in a predetermined plane generated by said registering feature, said plane has a fixed position relative to gemstone; e) working at least one facet and adjusting said fixture with gemstone with respect to said registering plane to set a working level and replacing said abrading article, and wherein replacement of one abrading article of said plurality of abrading articles by another does not require leveling of said gemstone or said abrading article.