WO1999037440A1

WO1999037440A1 - A method and assembly for diamond table polishing

Info

Publication number: WO1999037440A1
Application number: PCT/IL1999/000035
Authority: WO
Inventors: Zvi Porat; Akiva Caspi
Original assignee: Dialit Ltd.
Priority date: 1998-01-22
Filing date: 1999-01-20
Publication date: 1999-07-29
Also published as: AU2071699A; IL123030A0; IL123030A

Abstract

The invention provides a method for polishing a diamond table, including determining an optimal table and noting the parameters of the orientation of the table plane with respect to a zero angle of its yaw axis, its tilt angle with respect to a horizontal plane, and the amount of diamond material to be polished off the diamond in order to reach the optimal table; transferring the diamond to a polishing machine without altering its orientation with respect to the zero angle and the tilt angle; and polishing the diamond in accordance with the parameters. An assembly for implementing the method is also provided.

Description

1

A METHOD AND ASSEMBLY FOR DIAMOND TABLE POLISHING Technical Field

The present invention relates to diamond polishing and more particularly, to a method and an assembly for diamond table polishing. Background Art

Presently, table polishing is performed manually by affixing a rough diamond in a pot which is then attached to a holder by a bendable copper rod. The polisher, based on experience, then decides the following parameters: a) in which planar position the tilt has to take place; b) at what angle to tilt the copper rod; and c) how much material to polish out.

These decisions are carried out on a trial-and-error basis. Thus, in many cases, the polishing procedure does not compare favorably with the optimal potential of the rough diamond and inflicts losses on its owners.

While a more sophisticated, computerized apparatus has been developed for determining the optimum location of the table in a diamond rough, the implementation thereof has not as yet been developed or suggested. Disclosure of the Invention

Therefore, it is a broad object of the present invention to provide a method and an assembly for effecting optimal polishing of a diamond in accordance with a predetermined, computerized, table orientation decision.

In accordance with the present invention, there is thus provided a method for polishing a diamond table, comprising determining an optimal table and noting the parameters of the orientation of the table plane with respect to a zero angle of its yaw axis, its tilt angle with respect to an horizontal plane, and the amount of diamond material to be polished off the diamond in order to reach said optimal table; transferring said diamond to a polishing machine without altering its orientation with respect to said zero angle and said tilt angle; and polishing said diamond in accordance with said parameters. 2

The invention also provides a method for polishing a diamond table in accordance with table orientation parameters predetermined by an optical decision system, the method comprising calibrating said decision system by means of a calibration gauge to establish the zero position of the yaw axis of the table plane; transferring the established zero position onto a transfer base; estimating a face of the diamond to be polished and attaching the diamond to a stage having inde.xing means, with the estimated face to be polished contacting said stage; determining optimal table orientation by means of an optical decision system and recording determined parameters, including the angle of the pl.ane of said table in relation to said zero angle of the yaw axis, the tilt angle with respect to an horizontal plane and the amount of diamond material to be polished off the diamond for reaching said determined optimal table plane; transferring said diamond to a diamond holder without altering its orientation, to expose said face to be polished; and polishing said diamond in accordance with the recorded parameters.

The invention still .further provides an assembly for effecting diamond table polishing in accordance with table orientation parameters predetermined by an optical decision system, said assembly comprising a calibration gauge configured to set a zero angle of the yaw axis of the table plane when attached to said decision system; a transfer base mountable on said decision system for yaw -uάs alignment; a diamond attachment stage; and a diamond transfeiring device having registering means for assuring the transfer of said diamond from said stage to a polishing holder without changing the diamond's orientation parameters with respect to the yaw ajάs and tilt of the table to be polished as predetermined by said decision system. Brief Description of the Drawings

The invention will now be described in connection with certain preferred embodiments with reference to the following illustrative figures so that it may be more fully understood.

With specific reference now to the figures in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of 3

the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Fig. 1 is a perspective view of a preferred embodiment of a calibration gauge according to the present invention; Fig. 2 is a perspective view of a transfer base according to the present invention; Fig. 3 is a perspective view of a diamond attachment stage according to the present invention; Figs. 4, 4A, 5, 5A, 6 and 6A are side and top views, respectively, of a decision system in which the gauge, base and stage members of the assembly are sequentially mounted; Fig. 7 is a cross-sectional view of a diamond transferring arrangement; Fig. 8 is a perspective view of the diamond holder and polishing pot shown in cross- section in Fig. 7; Fig. 9 is a perspective view of a polishing machine utilized with the assembly according to the present invention; and Fig. 10 is an enlarged view of the adjustable arm of the machine of Fig. 9. Detailed Description

Referring to Figs. 1 to 7, there are shown preferred embodiments of the members forming the assembly for effecting optimal polishing of a diamond in accordance with a specific table location and orientation decision determined by a per se .known computerized diamond table location and orientation decision-malάng system (hereinafter, "decision system" or "system"), as illustrated in Figs. 4 to 7. Such a decision system DS is essentially composed of a camera C, a light source LS and a processor P. 4

The calibration gauge 2, seen in Figs. 1 and 4, is configured to set the zero position of the yaw axis of the plane of the chosen table. The disc-shaped calibration gauge 2 is formed with a diametrically extending slot 4 advantageously aligned with planar surfaces 6, 8 projecting from the upper surface of the gauge 2, together with a central stem 10. The gauge 2 is engaged with the decision system only when the system is activated. Upon the termination of the calibration step, gauge 2 is replaced by a transfer base 12 (Figs. 2, 5 and 5 A), generally configured similar to gauge 2 and having a diametrically extending groove 14 for yaw alignment at its lower surface and a pin 16 located along the axis of groove 14 and projecting from a recess 18 foimed in the upper surface of the base. A third member of the assembly according to the present invention (shown in Fig. 3), consists of a diamond attachment stage 20, sized to fit inside the recess 18 of the base 12, and having a diametrically emending slot 22 for accommodating pin 16. Stage 20 is also provided with a stem 24, onto which a rough diamond 26 to be polished is glued with quick glue, with the side of the diamond which was chosen to eventually be polished, facing and/or touching the upper face of stem 24.

Stage 20, with the diamond glued thereon, is then placed in recess 18 of base 12 of the system (Figs. 6, 6A) and the decision system measures the diamond and decides on the optimal location and orientation of the table to be polished. The decision system stores and/or displays on the screen data or parameters concerning the table angle, in terms of degrees offset from the zero yaw; the tilt angle with respect to the instant horizontal plane, and the number of microns that have to be polished off the diamond to obtain the optimal table.

Once the decision-mal ing operation is concluded, the stage with the diamond 26 to be polished is transferred to a diamond mounting device 28 (Fig. 7). This device is composed of a transfer plate 30 and a pressure-applying device 31, including a diamond polishing holder 32 (see also Fig. 8) ajdally movably affixable in a body 34, in alignment with the transfer plate. Diamond mounting device 28 is 5 advantageously made to accommodate a plurality of stages 20, supporting provisionally affixed diamonds 26.

The purpose of the mounting device is to fixedly mount the diamond with a determined orientation in a polishing tool by means of a holder and a pot, exposing the face to be polished which was previously glued onto the upper face of stem 24. Hence, as shown in Fig. 7, the transfer plate 30 is provided with a plurality of recesses 36, each having a pin 38 projecting therefrom and each sized so that a stage 20 fits closely therein, with the pin 38 engaging the slot 22 of the stage 20. Each of holders 32 is provided with a groove 40, facilitating its axial movement inside a hole 42 made in body 34. A pin 44 assures that the holder will not perfoim any angular movement inside hole 42. Thus, as can be understood, the pin 44 and groove 40 arrangement of holder 32 is aligned to be angularly identical with the pin 32 and groove 22 arrangement of transfer plate 30 and stage 20, so that the yaw positions are identical.

The lower portion of holder 32 outside of body 34 is designed to hold a replaceable polishing pot 46, having a diamond-accommodating bore 48, sized to accommodate diamonds of various dimensions, and a stem 50 to be fixedly attached to holder 32 by means of a screw (not shown) passing through a bore 52. The bore 48 of the pot, filled with regular table polishing glue and the body 34, is lowered so that a major portion of the diamond attached to stage 20 is immersed in the glue inside pot 46. In order to assure good contact between the diamond and glue inside the bore 48, a compression spring 54 is optionally provided for exerting the necessary pressure.

The two parts of the device 28 are clamped to each other and placed in an oven for a period of time, e.g., half an hour, causing the quick glue attaching diamond 26 to stem 24 to melt, while rigidifying the glue inside bore 48. Hence, in effect, the diamond as oriented with respect to the yaw axis of its table, is affixedly transferred to holder 32 while being released from stage 20.

The holder 32 with the diamond is now ready to be transferred to a diamond table polishing machine 56, shown in Fig. 9. The machine (not constituting part of 6 the present invention) has a control panel 58, enabling the operator to set the exact parameters for polishing, including: a) the amount of microns to be polished; b) the yaw angle of the table; c) the tilt angle; d) the pressure that the diamond should exert on the polishing wheel; e) the degree of difficulty in polishing the diamond; f) the amount, in percentage, to be polished, as defined in microns, in (a).

The machine 56 is also provided with a movable arm 60, seen to better advantage in Fig. 10 in an inverted orientation. .Arm 60 has a central bore, into which a holder 32 with a diamond mounted thereon is inserted. In Figs. 9 and 10, the holder 32 is shown without the diamond 26. Once the holder with the diamond is affixed inside the aim in a predetermined, angular position by means of a groove and pin arrangement identical or similar to the arrangement in the body 34, the yaw angle can be set, either manually or automatically, by rotating the yaw wheel 62 against the indej ng pointer 64. The screw 66 adjacent the arc 68 sets the tilt angle against the marker 70, either manually or automatically.

The diamond is then lowered onto the polishing wheel (not shown) and the polishing commences. The polishing direction is automatically found by the grain- seeldng mechanism. The machine counts each micron that is removed from the diamond by polishing, and once the preset amount of polishing is reached, the operation stops.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrated embodiments and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes 7 which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

8CLAIMS

1. A method for polishing a diamond table, comprising: deteimining an optimal table and noting the parameters of the orientation of the table plane with respect to a zero angle of its yaw axis, its tilt angle with respect to an horizontal plane, and the amount of diamond material to be polished off the diamond in order to reach said optimal table; transferring said diamond to a polishing machine without altering its orientation with respect to said zero angle and said tilt angle; and polishing said diamond in accordance with said parameters.

2. The method as claimed in claim 1, wherein the determination of said optimal table is effected by means of an optical decision system.

3. The method as claimed in claim 1, wherein said diamond is glued onto a support by means of quick glue for effecting the determination of said optimal table plane orientation, and mounted in a diamond holder by means of table glue, for transfer to a polishing machine.

4. The method as claimed in claim 3, wherein the transfer of said diamond from said support to said holder is effected simultaneously by means of heating.

5. A method for polishing a diamond table in accordance with table orientation parameters predetermined by an optical decision system, the method comprising: calibrating said decision system by means of a calibration gauge to establish the zero position of the yaw axis of the table plane; transferring the established zero position onto a transfer base; estimating a face of the diamond to be polished and attaching the diamond to a stage having indexing means, with the estimated face to be polished contacting said stage; determining optimal table orientation by means of an optical decision system and recording determined parameters, including the angle of the plane of said table in relation to said zero angle of the yaw axis, the tilt angle with respect to an horizontal 9

plane and the amount of diamond material to be polished off the diamond for reaching said determined optimal table plane; transferring said diamond to a diamond holder without altering its orientation, to expose said face to be polished; and polishing said diamond in accordance with the recorded parameters.

6. The method as claimed in claim 5, wherein said diamond is mounted onto said stage by means of quick glue.

7. The method as claimed in claim 6, wherein said diamond is transferred to said holder by immersing a portion thereof in a table glue inside a table pot and heating the diamond, to cause the melting of said quick glue and the simultaneous rigidifying of said table glue.

8. The method as claimed in claim 5, wherein each of a plurality of diamonds is simultaneously transferred to each of a plurality of diamond holders.

9. An assembly for effecting diamond table polishing in accordance with table orientation parameters predetermined by an optical decision system, said assembly comprising: a calibration gauge configured to set a zero angle of the yaw axis of the table plane when attached to said decision system; a transfer base mountable on said decision system for yaw axis alignment; a diamond attachment stage; and a diamond transferring device having registering means for assuring the transfer of said diamond from said stage to a polishing holder without changing the diamond's orientation parameters with respect to the yaw axis and tilt of the table to be polished as predetermined by said decision system.

10. The assembly as claimed in claim 9, wherein said diamond is attached to said stage by means of quick glue.

11. The assembly as claimed in claim 10, wherein said transferring device includes heating means and said diamond is affixed onto said holder by means of table glue, 10 and wherein, upon heating of said glues by said heating means, said quick glue melts and said table glue rigidifies.

12. The assembly as claimed in claim 11, wherein said transferring device comprises pressure-applying means for effecting positive contact between said diamond and said holder during the transfer operation.