Patent ID: 12202071

DETAILED DESCRIPTION OF EMBODIMENTS

FIG.1shows schematically a method100according to an embodiment of the invention. Steps of the method100are shown in a flow-diagram inFIG.2. The method100is suitable for manufacturing a workpiece101into a product102, by successively cutting away pieces of material from the workpiece101. The workpiece101may in particular be a rough diamond (see e.g.FIG.8), and the product102may in particular102be a brilliant (see e.g.FIG.7) or another facetted gem. The product102may be planned before performing the method100, wherein the planning may be based on the shape and volume of the workpiece101. To manufacture the product102, the method100successively cuts away pieces of material from the workpiece101until the desired complex product102shape is reached. For performing cutting, the method100makes use of an apparatus300(seeFIG.3) that provides a laser beam103coupled into a pressurized fluid jet104.

In particular, the method100comprises a step110of executing multiple cuts of the workpiece101with the laser beam103according to a predetermined cut-sequence105, in order to remove workpiece material with each completed cut. The predetermined cut-sequence105can be used as an input for the method100and/or to the apparatus300. The method100further comprises a step120of executing multiple rotations of the workpiece101around the same axis of revolution106according to a predetermined rotation-sequence107. The predetermined rotation-sequence107can be used as an input for the method100and/or to the apparatus300. The predetermined cut- and rotation sequences105and107can be generated when planning the product102based on the workpiece101.

In particular, a rotation is executed120after a completed cut. Further, for executing110a cut, the laser beam103is moved along a two-dimensional path108(relatively to the workpiece101). For moving the laser beam103, the apparatus300may be moved, or the workpiece101may be moved. A cut is completed, when a slice that was planned to be removed with this cut actually separates completely from the workpiece101. For completing a cut, the cut (i.e. the movement of the laser beam103along the two-dimensional path108associated with it) may be executed one or more times. For instance, executing the cut once may only form a narrow groove in the workpiece101, the groove having a certain depth. Executing the cut again may deepen the groove, and executing the cut again (and again) may extend the groove completely through and across the workpiece so that a slice falls off.

FIG.3shows an apparatus300according to an embodiment of the invention. The apparatus300is configured to manufacture a workpiece101into a product102, and may be the apparatus300used in the method100. The apparatus300comprises at least a machining unit302, a control unit303, and an optical sensor301.

The machining unit302is configured to provide a laser beam103coupled into a pressurized fluid jet104. The control unit303is configured to control the machining unit302. In particular, it may control the machining unit302to: execute multiple cuts of the workpiece101with the laser beam103according to a predetermined cut-sequence105to remove workpiece material with each completed cut, and to execute multiple rotations of the workpiece101around the same axis of revolution106according to a predetermined rotation-sequence107. Thereby, a rotation is executed after a completed cut, and the laser beam103is moved for executing a cut along a two-dimensional path108. These actions may implement the method100ofFIG.1andFIG.2. The optical sensor301is configured to determine at least each of the following conditions: an executed cut was completed; an executed cut was not completed. Optionally it may also determine the condition: no workpiece material was removed at all by executing a cut.

The machining unit302may couple the laser beam103—e.g. received from a laser source305, which may optionally be a part of the apparatus300, or e.g. from multiple laser sources—into the fluid jet104. This coupling is preferably done in the machining unit302. During the manufacturing of the product102, the workpiece101may be positioned on a machining surface, which may or may not be part of the apparatus300. In either case, the apparatus300can be arranged such that it is able to machine the workpiece101disposed on the machining surface. The apparatus300may thereby control movements of the machining surface in up to three dimensions (e.g. in x-y-z as indicated inFIG.3, wherein the z-direction is parallel to the fluid jet104, and the x- and y-directions are perpendicular to the z-direction and to each other). The apparatus300is in particular able to cut the workpiece101by moving the fluid jet guided laser beam103along a cutting path, in particular a two-dimensional path108, like a straight and/or arc, over the workpiece101. The movement may thereby be continuous or stepwise, and a speed of the movement may be selected/changed.

The machining unit302may particularly include an optical element, like at least one lens307, for coupling the laser beam103into the fluid jet103. The laser beam103is preferably produced outside of the machining unit302, and is injected into the machining unit302. In the machining unit302, a mirror or beam splitter308or another optical element may guide the laser beam103towards the at least one lens307. The beam splitter308may also be used to couple part of the laser light, or electromagnetic radiation coming from the workpiece101, to the optical sensor301. The machining unit302may also include an optically transparent protection window310, in order to separate the optical arrangement, here exemplarily the optical element308, from the fluid circuitry and from the region of the machining unit302where the fluid jet104is produced.

For producing the fluid jet104, the machining unit302may include a fluid jet generation nozzle309having an aperture. The fluid jet generation nozzle is preferably disposed within the machining unit302to produce the fluid jet104in a protected environment. The aperture defines the width of the fluid jet104. The aperture may have, for example, a diameter of 10-200 μm, and the fluid jet104may have, for example, a diameter of about 0.6-1 times the aperture. The pressure for the pressurized fluid jet104is preferably provided via an external fluid supply304, which is typically not part of the apparatus300(but can be). Preferably, the pressure is between 50-800 bar. For outputting the fluid jet104from the apparatus300, the machining unit302may include an exit nozzle with an exit aperture. The exit aperture is preferably wider than the fluid nozzle aperture.

The control unit303may further control the at least one laser source305(e.g. may command a laser controller of the laser source305). That is, the control unit303may instruct a laser controller of the laser source305to output an according laser emission. The laser controller of the laser source305may thereby be able set a constant or pulsed laser beam, for the latter particularly to set a pulse power, pulse width, pulse repletion rate, pulse burs rate, or a pause between pulses according to the instructions of the control unit. The control unit303may also control the fluid supply304.

The workpiece101may be coupled with or attached to a rotatable part306of the apparatus300, e.g. a rotatable part driven by a motor or CNC. For instance, the rotatable part306of the apparatus300may be a rod or a so-called “Dop”. The rotatable part306may be at least 10% smaller, particularly at least 20% smaller (in diameter/width), than the workpiece101diameter. The rotatable part306rotates around the axis of revolution106. The rotation of the rotatable part306may be controlled by the control unit303, particularly based on an input from the optical sensor301.

The optical sensor301may be arranged to receive a laser-induced electromagnetic radiation that propagates away from the workpiece101(while cutting the workpiece101) through the fluid jet104and through at least one optical element307,308towards the sensor301. The sensor301may in particular be arranged to receive the laser-induced electromagnetic radiation through the fluid jet104and through the at least one optical element307, which is configured to couple the laser beam103into the fluid jet104. The laser-induced electromagnetic radiation may include secondary radiation emitted from a portion of the workpiece101that is cut with the laser beam103. For instance, the laser-induced electromagnetic radiation may be induced because the cut surface region of the workpiece is transformed into a plasma. This plasma may emit a characteristic radiation, which can be easily isolated on or by the sensor301. The laser-induced electromagnetic radiation may also include primary laser radiation that is reflected from the workpiece101. The laser-induced electromagnetic radiation may also include secondary radiation generated by scattering, preferably Raman scattering, of the laser beam103in the fluid jet104.

The optical sensor301may be arranged in the machining unit302. However, it may also be arranged in the laser source305. In this case, laser-induced radiation may back-propagate from the workpiece101, and may be guided through the machining unit302to the laser source305, where it is received by the sensor301. The machining unit302can be optically connected to the laser source305, for instance, by an optical fiber.

Further, the sensor301may be configured to convert the received radiation into a signal. The control unit303may include processing circuitry configured determine a state of machining the workpiece based on the signal. The state of machining the workpiece101may be whether the laser beam103has broken through the workpiece101. The control unit303is in particular configured to determine whether an executed cut was completed, whether an executed cut was not completed, and/or whether no workpiece material was removed at all by executing a cut.

The apparatus300, in particular the control unit303, may comprise a processor or processing circuitry (not shown) configured to perform, conduct or initiate the various operations of the apparatus300described in this disclosure, in particular to perform the method100. The processing circuitry may comprise hardware and/or the processing circuitry may be controlled by software. The hardware may comprise analog circuitry or digital circuitry, or both analog and digital circuitry. The digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), digital signal processors (DSPs), or multi-purpose processors.

The apparatus300may further comprise memory circuitry, which stores one or more instruction(s) that can be executed by the processor or by the processing circuitry, in particular under control of the software. For instance, the memory circuitry may comprise a non-transitory storage medium storing executable software code or program code, which, when executed by the processor or the processing circuitry, causes the various operations of the apparatus described in this disclosure, in particular causes the method100to be performed.

FIG.4shows a flow-diagram of the method100according to an embodiment of the invention, which builds on the method100shown inFIG.1andFIG.2, and may be carried out by the apparatus300. Same elements in the figures are labelled with the same reference signs and function likewise.

In the method100ofFIG.4, in a first step400, a next cut to be executed is selected from the predetermined cut-sequence105. Then the cut is executed110once. If it is determined401that the execution110of the cut has stopped, a verification402of the cut is made. That is, after the executed cut, it is verified, whether the cut was completed or not. This is done by means of the optical sensor301and/or the control unit303.

The verification can determine that the cut is successfully completed, which is illustrated inFIG.5(b), where the cut along the two-dimensional path108has resulted in slicing off the workpiece material as planned. In this case, the workpiece101can afterwards still be rotated by an angle, particularly by an angle of 180°, and then the same cut can be executed110again. If it is further determined that the same cut executed100after rotating the workpiece101is also completed, the method100may proceed. This is the 180° corrective action mentioned above.

Alternatively, as shown inFIG.5(a)the fluid jet104can be moved away from the workpiece101to a position (e.g. within a determined verification area as indicated by the rectangular box), where material should have been removed from the workpiece101by completing the cut (inFIG.5(a)it actually is sliced off). The laser beam103can be turned on at that position, and it can be determined (e.g. by performing a cut along a dummy path500), whether there is still workpiece material at the determined position or not.

The verification can also determine that the cut is not successfully completed, as shown inFIG.5(c), where the cut along the path108has not yet sliced off the workpiece material. In this case, the method100continues the cutting. That is the same cut is executed110again, one or multiple times, without rotating the workpiece101in between, if determining that the cut was not completed. This may proceed until determining that the cut is completed.

After the cut is completed, and optionally verified, the method100can determine whether the entire predetermined cut-sequences105is completed or not, i.e. whether all cuts in the cut-sequence105were executed and determined completed. If yes, the method100ends. If not, the method100proceeds to the next cut in the cut-sequence105. A rotation according to the predetermined rotation-sequence107is executed120before the next cut.

FIG.6shows an example of a sensor signal, which may be analyzed by the control unit303. The control unit303can identify based on the sensor signal, whether an executed cut was successful (completed) or not. For instance, if the electromagnetic emission from the workpiece101, which is induced by the laser cutting, drops below a determined threshold value, in particular for a certain amount of time, a successful cut can be determined. Above the determined threshold value, the cut may be determined not successful. If the sensor signal remains below the determined threshold value, so that the control unit303determines “successful”, the 180° corrective action or the alternative verification area cut can be performed. If in this case the signal rises again above the determined threshold value (as indicated by the dotted arrow inFIG.6), the initial determination of the cut being “successful” was incorrect. If, however, the signal stays below the determined threshold value, the initial determination of the cut being “successful” is confirmed.

As mentioned before, the method100and apparatus300are in particular suitable to manufacture a brilliant or other facetted gem. A typical brilliant700is shown inFIG.7. The brilliant700includes a plurality of facets701. The brilliant700includes an upper part700a(the crown) and a lower part700b(the pavilion). The parts are separated/connected by the girdle704, which may have multiple girdle facets. The lower part700bincludes pavilion facets702and lower girdle facets703. The upper part700aincludes upper girdle facets705, bezel facets706, and star facets707. The brilliant700has also a table708.

FIG.8shows schematically a method100according to an embodiment of the invention, which builds on the method100shown inFIG.1. Same elements are labelled with the same reference signs and function likewise. InFIG.8, the workpiece101is a rough diamond800, and the product102is a brilliant700. The laser beam103and fluid jet104may be oriented perpendicular to the axis of revolution106. The facets701of the brilliant700are cut by rotating around the axis of revolution106, and moving the laser beam103along two-dimensional paths108. The cutting110according to the predetermined cut-sequence105and the rotating 120 according to the predetermined rotation-sequence107are performed as described for the method100ofFIG.1andFIG.2. The pavilion facets702may be cut first, in order to remove larger pieces of rough diamond such that B-Stones802and C-Stones801can be produced from these pieces. That is, pavilion facets702may preferably be produced before lower girdle facets703. Further, the girdle704may be cut, then bezel facets706, then upper girdle facets705, then star facets707. The table708of the brilliant700is preferably pre-produced, so that the rough diamond800can be attached with the table708to the rotating part306of the apparatus. The configuration shown inFIG.8is suitable for the “side-on” cutting strategy.

FIG.9shows that the axis of revolution106can also be non-perpendicular to the laser beam103and fluid jet104, respectively, i.e. they can be aligned oblique to another.FIG.9(a)shows that in this case a table708of the brilliant700may be oriented towards the apparatus300(the laser beam103comes from above, as indicated by the arrow), whileFIG.9(b)shows that also a culet or tip of the brilliant may be oriented towards the apparatus300. The configurations shown inFIG.9are suitable for the “end-on” cutting strategy, particularly for the “culet-up” or “table-up” cutting strategies.

The different cutting strategies proposed in this document are respectively illustrated inFIGS.10,11and12.FIG.10shows a “side-on” cutting strategy.FIG.12shows “end-on” cutting strategies, particularly “culet-up” inFIG.12(a)and “table-up” inFIG.12(b).FIGS.11(a) and (b)shows “one-direction” cutting strategies, particularly in combination with the “side-on” cutting strategy, i.e. “uphill” inFIG.11(a)and “downhill” inFIG.11(b). Notably, a “one-direction” cutting strategy can also be combined with an “end-on” cutting strategy.FIGS.11(c) and (d)show “grouped fresh” and “grouped-rough” cutting strategies, respectively, particularly in combination with the “side-on” cutting strategy. Notably, a “grouped” cutting strategy can also be combined with an “end-on” cutting strategy.

A preferred cutting strategy combination for cutting a brilliant700from a diamond800combines “side-on”, “back-and-forth” and “grouped-fresh”.

In particular, it can be seen inFIG.10that “side-on” means that the laser beam103is always moved along the length L of the facet701to be produced, in order to execute110a cut. That is, towards and/or away from an apex1000of the brilliant facet701.FIG.10particularly shows “side-on” in combination with the “back-and-forth” cutting strategy, according to which the laser beam103is moved along the two-dimensional path108back and forth (i.e. in both ways), in order to execute110a cut multiple times.FIG.10also illustrates, by showing the orientation of the pavilion700bof the brilliant, that along the length means in a direction from culet to table708or vice versa.

FIGS.11(a) and (b)show “one direction” cutting strategies, according to which the laser beam103is moved along the two-dimensional path108always in the same direction, in order to execute110a cut multiple times. InFIG.11(a)the strategy is “uphill”, i.e. the laser beam103is always moved away from apex1000of the facet701(towards its base) to execute110a cut, whileFIG.11(b)shows “downhill”, i.e. the laser beam103is always moved towards the apex1000of the facet701(away from its base) to execute110a cut.

FIGS.11(c) and (d)show “grouped” cutting strategies, in which a first group of discontiguous lower girdle facets703, particularly left lower girdle facets703or right lower girdle facets703, is produced before a second group of discontiguous lower girdle facets703, particularly right lower girdle facets703or left lower girdle facets703, respectively, is produced.FIG.11(c)shows the “grouped fresh” strategy, according to which the laser beam103is positioned on a previously produced (fresh) facet1100to execute110a cut.FIG.11(d)shows the “grouped rough” strategy, according to which the laser beam103is positioned on an uncut surface1101of the rough diamond700to execute110a cut.

FIGS.12(a) and (b)show “end-on” strategies, according to which the laser beam103is always moved along the width W of the facet701to execute110a cut. Width may be perpendicular to length L shown inFIG.10.FIG.12(a)shows a “culet-up” strategy, according to which a culet faces (is oriented towards) the apparatus300(seeFIG.9b).FIG.12(b)shows a “table-up” strategy, according to which a table faces (is oriented towards) the apparatus300(seeFIG.9a).FIG.12also illustrates, by showing the orientation of the pavilion700bof the brilliant700, that along the width means e.g. in a direction parallel the girdle704.

The present invention has been described in conjunction with various embodiments as examples as well as implementation forms. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed invention, from the studies of the drawings, the description and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.