EP3253533B1

EP3253533B1 - Apparatus for simultaneously machining a plurality of precious stones

Info

Publication number: EP3253533B1
Application number: EP16710005.6A
Authority: EP
Inventors: Mario Gaia
Original assignee: Gaia Mario
Current assignee: Gaia Mario
Priority date: 2015-02-05
Filing date: 2016-01-29
Publication date: 2018-05-02
Anticipated expiration: 2036-01-29
Also published as: WO2016125057A1; ITUB20150159A1; EP3253533A1

Description

Field of the invention

The present invention relates to an apparatus for simultaneously machining several precious stones, diamonds, semiprecious stones, decorative crystals and glasses, drill bits having very high hardness, in particular an apparatus designed for simultaneously grinding, lapping and polishing tens, hundreds or thousands of precious stones also for industrial use.

State of the art

Traditionally, precious stones and industrial diamonds are machined one by one by artisans, by means of machines of the type described in US Patent 4,287,687 . These machines are provided with a rotating lap and a head able to be oriented with respect to the lap. Usually the lap is of the diamond-type, i.e. coated by diamond powder. The head is composed of a finger movable on a slide and swinging around a pin. The stone to be machined is fixed, usually by glue, to one end of the head which is handled and oriented by the artisan, who pushes the stone against the moving lap in order to make a facet on the stone. From time to time, the orientation of the head is changed by the artisan in order to achieve a new facet on the stone.
Other examples are described in CN 201537846(U ) and CN 202053151(U ).
Machines based on the same concepts, but able to batch at any one time ten or more stones, have been proposed. For example, Korean Patent Applications KR 2004097826 and KR 2004101734 describe such solutions.
Other solutions for machining stones of small diameter, about 1 - 5 mm, which provide a plurality of parallel pins carrying the stone holding head, arranged as aligned and movable with respect to the lap, are further known. The number of heads is generally between 100 and 200 and the length of the row of heads is mostly between 300 and 600 mm.
The most evident limit of the solutions today available is precisely that they are able to machine a limited number of stones per each batch. In other words, the productivity of the machines is limited by the maximum number of stones that can be simultaneously machined.
WO 2005/021212 A1 discloses the features of the preamble of claim 1.

Summary of the invention

Therefore, object of the present invention is to provide an apparatus for machining precious stones, industrial diamonds, etc., which allows to effectively machine at the same time a large number of stones, even hundreds or thousands.
Therefore, the present invention concerns an apparatus according to claim 1 for machining precious stones or similar, for example industrial diamonds and zircons, semiprecious stones, decorative crystals and glasses, drill bits having very high hardness and particularly for grinding, lapping and polishing these stones.
In more detail, the apparatus comprises at least one lap or an equivalent abrasive member, at least one supporting assembly to support the stones to be machined; the stones can be interchangeably constrained to the supporting assembly so that, when a stone has been completely machined, a new stone to be machined can be constrained to the supporting assembly.
The supporting assembly comprises in its turn:

a stone holding member, hereinafter named socket, provided with a housing seat wherein the stone to be machined can be partially inserted;
at least three supporting stems to support the socket, each constrained to the socket at a side opposite to the housing seat of the stone to be machined. Preferably, the supporting stems are constrained to corresponding housing seats obtained in the socket, according to a triangular pattern.

The supporting stems, which can also be defined as supporting rods, legs or fingers, each extend along its own longitudinal axis, i.e. the respective length is the main size.
The supporting assembly and the respective lap are movable with respect to one another between a distal position at which the stone, temporarily set in the socket, does not interact with the lap, and a proximal position at which the stone in the socket contacts the lap to be either ground, or lapped or polished at a facet.
Advantageously, each supporting stem is constrained to the socket so that to be able to be oriented with respect to it, i.e. by spherical motion. Within the same supporting assembly, at least one first stem and one second stem are translatable in the two ways along their own longitudinal axis and the third stem is stationary, or else it is translatable too in the two ways along its own longitudinal axis.
The described arrangement is advantageous because the instantaneous position adopted each time by the three supporting stems defines univocally the orientation of the socket and, therefore, the orientation of the stone housed therein, with respect to the respective lap. Therefore, by moving the supporting stems each time to a new position, the stone can be correspondingly oriented with respect to the lap in order to machine a facet. As a result, by mechanizing and automating the movement of the supporting stems, it is therefore possible to quickly machine several facets on the same stone.
By preparing a multitude of supporting assemblies within the same apparatus, as will be described later, a corresponding number of stones can be simultaneously machined.
Preferably, the coupling among the supporting stems and the socket is of spherical type, i.e. every stem is provided with a spherical head and the socket is provided with a corresponding spherical seat, or vice versa, so that the socket can tilt with respect to the longitudinal axis of the stem. Additionally, or alternatively, the coupling is magnetic, i.e. in addition to a shape coupling, a magnetic coupling can be provided between the heads of the supporting stems and the corresponding seats obtained in the socket.
In order to have a large number of supporting assemblies, preferably the apparatus comprises a stem-holding rule per each supporting stem. The stem-holding rule, for example a metal one, is fixed to the respective supporting stem or is made integral therewith starting from a laser-cut metal foil. The stem-holding rule extends orthogonal with respect to the respective supporting stem. The stem-holding rule has the function of imparting its translation movement in the two ways of the length of the stem; clearly, in this arrangement the rule and the stem move together in unison, jointly.
In the embodiment in which the supporting assembly has three supporting stems, the apparatus comprises three corresponding stem-holding rules. Preferably, the apparatus also comprises at least one supporting frame to support the stem-holding rules and:

at least two supporting rules are movable closer and away one to/from another, with very little travels, and/or
at least two supporting stems are flexible,

The socket can take all positions required for machining the facets of the stone without causing the support stems to break, bend or separate from the socket, due to the possibility to adjust the transverse position of at least two stem-holding rules or to provide that at least two supporting stems can flex slightly.
As mentioned above, in the preferred embodiment of the present invention the apparatus comprises a plurality of supporting assemblies for simultaneously machining a corresponding number of stones. The supporting assemblies are arranged as aligned on a single assembly of respective stem-holding rules, i.e. n first supporting stems are fixed to, or integral with, the same first stem-holding rule, n second supporting stems are fixed to, or integral with, the same second stem-holding rule and n third supporting stems are fixed to, or integral with, the same third stem-holding rule. As a result, a row of supporting assemblies is obtained where the instantaneous position taken by every socket can be adjusted by acting on the three shared stem-holding rules.
Tens of supporting assemblies, or even more than one hundred, can be arranged in a same row.
More preferably, the supporting assemblies are arranged as determined by an array comprising a plurality of lines placed side by side, and corresponding assemblies of stem-holding rules. In other words, preferably the apparatus comprises an array of supporting assemblies, which is made up of several rows placed side by side, where the supporting assemblies in a row share the stem-holding rules, such as common feet. This arrangement allows hundreds or thousands of supporting assemblies to be effectively placed in a minimum space, that is to say within a much smaller area compared to the space requirements of the prior art machinery, although being able to simultaneously machine the same number of stones.
Preferably, every socket of the supporting assemblies in the apparatus is joined to/by an elastic blanket or a protecting sheath, for example made of silicone, to protect from the dust.
In a particularly effective variation, the volume underlying the protecting sheath can be depressurized in order to generate a force able to keep the sockets always coupled with the respective supporting stems, and to prevent the sockets from inadvertently and undesirably come out from the respective stems due to the friction caused by the interaction between the stones and the lap. In practice, when the air under the sheath is depressurized, a force pushing the sockets against the supporting stems is generated. What is needed is to provide suction means for sucking air inside the supporting frames of the stem-holding rules.
As mentioned, the stem-holding rules are needed to drive the movements of the supporting stems. The best way to operate the stem-holding rules is to combine the respective supporting frame with one or more actuators, for example electrical or pneumatic linear actuators, which are responsible for causing such movements. For example, all the first stem-holding rules of the array are coupled with a first frame, all the second stem-holding rules of the array are coupled with a second frame and all the third stem-holding rules of the array are coupled with a third frame. At least two of the three frames are coupled with actuators which drive their positioning in the longitudinal direction, i.e. parallel to the length of the supporting stems, in order to cause the respective supporting stems to cover a corresponding longitudinal travel and, as a result, to orient the socket, and therefore the stone, with respect to the lap.
This arrangement can be achieved with at least two structural embodiments: in a first embodiment, the three frames are stacked on top of one another, in a second embodiment they are arranged one inside the other, on the same level.
Among the frames a clearance is left corresponding to the travel the movable frames must be able to cover in order to move the supporting stems.
Then every frame is mounted on a movable arm rotating with respect to the lap. The arm has to bring the supporting assemblies with the stones into contact with the lap and away therefrom.

Brief list of the figures

Further characteristics and advantages of the invention will be more evident by the review of the following specification of a preferred, but not exclusive, embodiment depicted for illustration purposes only and without limitation, with the aid of the attached drawings, in which:

figures 1-3 are schematic perspective views of a detail of the apparatus according to the invention;
figure 4 is a schematic elevation view of the detail shown in figures 1-3;
figure 5 is a schematic top view of the detail shown in figures 1-3;
figure 6 is a schematic elevation view of a detail of the apparatus according to the present invention, in a first arrangement;
figure 7 is a schematic elevation view of a detail of the apparatus according to the present invention, in a second arrangement;
figure 8 is a schematic elevation view of a detail of the apparatus according to the present invention, in a third arrangement;
figure 9 is a schematic plan view of a precious stone in progress;
figures 10 to 12 are schematic perspective views of a member of the apparatus according to the present invention, in three corresponding arrangements;
figures 13 to 18 are schematic views of the member shown in figures 10-12, in corresponding arrangements;
figure 19 is a perspective view of a group of components of the apparatus according to the present invention;
figure 20 is a schematic perspective view of an apparatus according to the present invention;
figure 21 is a schematic perspective view of a group of members of the apparatus according to the present invention;
figure 22 is a schematic cross sectional view of a detail of the apparatus according to the present invention;
figure 23 is a schematic elevation side view of the apparatus according to a first embodiment of the present invention;
figure 24 is a vertical section view of the apparatus shown in figure 23, examined on the plane X-X;
figure 25 is a vertical section view of the apparatus shown in figure 23, examined on the plane Y-Y;
figure 26 is a vertical section view of an apparatus of a second embodiment of the present invention, examined on the plane A-A of figure 27;
figure 27 is a vertical section view of the apparatus shown in figure 26, examined on the plane B-B of figure 26;
figure 28 is a perspective view of a component of the apparatus shown in figure 26.

Detailed description of the invention

In order to facilitate the understanding of the structure and the technical characteristics of the apparatus according to the present invention, it is convenient to describe firstly the main components and then, at a later time, describe the apparatus as a whole.
Figures 1 to 5 relate to the core of the invention, the supporting assembly 1 of the stones to be machined. The supporting assembly 1 comprises, in turn, a member 2 for containing precious stones S, i.e. an element called socket, provided with a housing seat 3 designed to interchangeably house a portion of the stone to be machined, so that a portion of the stone S protrudes from the socket thereby being able to be brought in abutment against a lap or an equivalent abrasive or polishing element. For example, the stone S is fixed in the housing seat 3 by glue.
The supporting assembly 1 further comprises at least three feet, or legs, hereinafter called supporting stems 10, 20 and 30, each provided with a substantially spherical head, respectively 11, 21 and 31, engaging in a respective housing seat obtained in the socket 2, respectively 12, 22, 32, so as to be able to be oriented.
Figures 1 and 2 show the assembly 1 in top and bottom perspective views and in exploded views. Figure 3 shows a perspective bottom view of the assembled supporting assembly 1. Figure 4 is a conceptual schematic view. Figure 5 shows the assembly 1 as seen from above, i.e. from the side of the stone S.
A shape coupling is obtained between the spherical heads 11, 21 e 31 and the respective housing seats 12, 22 and 32, but at least one of the spherical head and the respective housing seat is preferably magnetic. In other words, preferably, the coupling is both a shape and magnetic coupling so as to minimize the risk for the socket 2 to accidentally detach from the supporting stems 10-30.
Alternatively or in addition to the mechanical and/or magnetic coupling, the apparatus may be provided with an elastic blanket, or sheath, and means for depressurizing the air under the sheath, in order to make sure that the sheath adheres to the sockets and holds them against the supporting stems, as will be described later.
The supporting stems 10-30 are integral with the respective stem-holding rules 100, 200 e 300. The supporting stems extend in a longitudinal direction, i.e. depending to their length which is prevalent with respect to the other dimensions, while the stem-holding rules extend orthogonal to the stems. The function of the supporting stems 10-30 and the stem-holding rules 100-300 will be explained later. It should be noted herein that the supporting stems 10-30 must be coupled with the socket 2 in such a way that the stems 10-30 are able to orientate in space with respect to the socket 2 or, vice versa, the socket 2 is able to tilt with respect to the stems 10-30.
Figures 6-8 illustrate the operation of the supporting assembly. The reference M schematically indicates an abrasive lap moving with respect to the stone S with a translation speed at least locally substantially orthogonal with respect to the supporting stems of the sockets 2. In practice, the plane in which the abrasive surface of the lap lies is orthogonal to the supporting stems 10-30.
Focusing on Figure 6 and considering stationary the supporting stem 30, the left supporting stem 10 is lifted and, therefore, it moves closer to the stem 30, and the right supporting stem 20 is lowered and, therefore, it moves closer to the stem 30 too. According to an arrangement not shown in figures, the supporting stems 10-30 do not move closer to each other, but they simply flex. By positioning the supporting rods 10-30 in this way, the spatial orientation of the socket 2 is univocally determined and corresponds to machining the facet F2 of the stone S, this facet being highlighted in Figure 9. In practice, the lifting of the supporting stem 10 and the lowering of the other stem 20 result in a side tilt of the socket 2.
Figure 7 shows the situation when the supporting stems 10-30 are aligned, i.e. the respective heads are located at the same height. In this circumstance, the socket 2 is not tilted, but its symmetry axis remains vertical and the top facet F1 is machined by the lap (figure 9). The supporting stems do not move closer or flex in order to move the respective heads 11, 21, 31 closer to each other.
Figure 8 shows another positioning of the socket 2. The left supporting stem 10 is lowered and, therefore, it moves closer to the stem 30, and the right supporting stem 20 is lifted and, therefore, it moves closer to the stem 30 too. By positioning the supporting rods 10-30 in this way, the spatial orientation of the socket 2 is univocally determined and corresponds to machining the facet F3 of the stone S, this facet being highlighted in Figure 9. In practice, the lifting of the supporting stem 20 and the lowering the other stem 10 results in a tilt of the socket 2 on the opposite side with respect to the position shown in figure 6.
The reference number 4 denotes an elastic sheath fitting on all sockets 2 in the apparatus. The sheath 4 is intended to protect, from the dust generated by the machining, the supporting stems 10-30 and everything lying under the socket 2. Furthermore, the sheath 4 is intended to allow to depressurize the volume underlying the sockets 2. This function will be better described below.
The sheath 4 comprises a plurality of holes corresponding to the sockets 2. The edge of the holes in the sheath 4 sealingly adheres to the sockets 2, as shown in figures 6-8 and 21.
Figures 10-12 show the same row 5 of supporting assemblies 1 at corresponding positions. The row 5 comprises three stem-holding rules 100, 200, 300 on which several supporting assemblies 1, in this specific case six, are provided. The supporting stems 10-30 are integral with the respective stem-holding rule 100-300 so that by moving a rule 100, 200 or 300, a corresponding movement of every supporting stem 10 or 20 or 30 combined therewith is caused.
This structure therefore allows to orient in space, and thus with respect to the lap M, six sockets 2 at the same time, all with the same orientation.
For example, figure 10 shows the row 5 of supporting assemblies 1 arranged in such a way that all the sockets 2 are tilted in order to machine the facet F3 of the set stones S, figure 11 shows the row 5 of supporting assemblies 1 arranged in such a way that all the sockets 2 are upright in order to machine the facet F1 of the set stones S and figure 12 shows the row 5 of supporting assemblies 1 arranged in such a way that all the sockets 2 are tilted in order to machine the facet F5 of set stones S.
Hence, by suitably orienting the supporting assemblies 1 by acting on the stem-holding rules 100-300 and possibly by rotating the stem-holding rules 100-300 with respect to a lap M, all the facets of the stones S can be successfully machined at the same time.
This concept is schematically illustrated in figures 13 to 18.
In particular, figures 13-15 show the row 5 of supporting assemblies 1 in a side view, i.e. the side of the stem-holding rules 100-300 can be seen. The movement given to the stem-holding rules 100-300 results in a corresponding and univocal spatial orientation of the sockets 2 and, therefore, a corresponding facet of the stones S is led into contact against the lap M.
Figures 16-18 show the same positions, but in a front sectional view, i.e. a cross-section of the stem-holding rules 100-300. Figure 16 corresponds to figure 13, figure 17 corresponds to figure 14 and figure 18 corresponds to figure 15.
In figures 13-18 the arrows show the movements imparted to the stem-holding rules 100-300 starting from the initial position shown in figure 14 and figure 17.
Figure 19 shows the core of the apparatus according to the present invention, comprising a plurality of rows 5 of supporting assemblies 1 arranged as determined by an array 500. The stem-holding rules 100-300 of every row 5 are constrained to a supporting frame 600 provided with the actuators 6 and 7, for example linear actuators.
The actuators 6 are intended to drive the vertical movements of the stem-holding rules 100-300 and the actuators 7, which are optional, are intended to drive the horizontal movements of the rules 100-300, that is those small movements that can be defined as adjusting movements and are able to compensate the movements of the spherical heads 11, 21 and 31 as they move closer and away.
In practice the actuators 6, suitably driven by a control unit not shown in the figures - for example of the electronic type such as a computer, a PLC unit, etc. -, cause all the sockets 2 of the array 500 to simultaneously orientate, acting as a field of sunflowers.
For the sake of simplicity, in figure 19 all the sockets 2 in the array 500 are shown in the upright position, i.e. with the symmetry axis vertical and oriented downwards, i.e. towards the lap (not shown in this figure).
As mentioned, the actuators 7 may be absent, for example in the case in which the stem-holding rules 100-300 are slidably mounted on the frame 600, which may consist of metal rods.
Figure 20 schematically shows the apparatus according to the present invention. The array 500 and the frame 600 are constrained to an arm 8 able to lead the array 500 in abutment against the moving lap M. Furthermore, in its turn, the arm 8 is able to be oriented so that the facet of the stones S to be machined at a given instant is offered to the lap.
Certainly the field technician will appreciate that by selectively acting on:

the stem-supporting rules 100, 200 and 300 by means of the actuators 6 and/or 7;
the arm 8 as it lifts, lowers and is angularly positioned;

array

The function of the sheath 4 is best shown in figure 21. For the sake of simplicity, it is still possible to see the structure of the frame 600 and array 500, whereas in practice the whole is intended to be confined in an envelope not shown in this figure. Well, the volume under the sheath 4, i.e. the volume of the portion of the stem-holding rules 100-300, can be depressurized for example by means of an extractor so that the sheath 4 is partially sucked downward, that is towards the stem-holding rules 100-300. In this way, the sheath holds the sockets 2 on the supporting stems 10-30; in practice, the sheath pushes the sockets 2 against the supporting stems 10-30 thereby ensures that the detachment of the sockets 2 is avoided in use.
Figure 22 is a sectional schematic view of the assembly shown in figure 21. The V letter denotes the volume able to be depressurized in order to push the sheath 4 downward, as depicted by the respective arrow.
Figure 23 is a side elevation view of an apparatus 1000 according to the present invention, in a first variation.
Figure 24 is a sectional view of the array 500 and frame 600, examined along the plane X-X of figure 23.
Figure 25 is a partial sectional view of the array 500 and frame 600, examined along the plane Y-Y of figure 23.
Considering figures 23-25, in this embodiment the frame 600 is of the box-type and consists, in its turn, of three boxes 601, 602 and 603 arranged one inside another at the same level. Each box 601-603 is provided with a plurality of horizontal metal rods, respectively 610, 620 and 630, on which the stem-holding rules 100-300 are mounted.
For example, the box 602 comprises a plurality of rods 620 on which only the stem-holding rules 200 are constrained; the box 602 is combined with at least one linear actuator 6 driving the movements thereof in a vertical direction in order to cause corresponding movements of all the supporting stems 20.
For example, the box 603 comprises a plurality of rods 630 on which only the stem-holding rules 300 are constrained; the box 603 is combined with at least one linear actuator 6 driving the movements thereof in a vertical direction in order to cause corresponding movements of all the supporting stems 30.
For example, the box 601 comprises a plurality of rods 610 on which only the stem-holding rules 100 are constrained; the box 601 is stationary, i.e. it is not combined with an actuator because, in the embodiment shown in figures 23-25, the stem-holding rules 100 are not expected to move.
Among the three boxes 601, 602 and 603 a clearance is provided, which can be seen in figures, to allow the boxes to move one inside the other according to the travels imparted by the actuators 6, in order to move the supporting stems 10-30.
Figure 24 shows the sheath 4 when the air contained in the volume V is sucked, thereby depressurizing the latter. Even when the friction generated by the stones S sliding on the lap M is high, the sockets 2 are still held against the supporting rods 10-30.
Figure 26-28 show a second variation of the apparatus 1000 with respect to the variation shown in figures 23-25. The sheath 4 is omitted for better clarity. In this variation, the boxes 601, 602 and 603 are positioned on top of one another instead of being aligned inside one another as in the previously described case.
Also in this variation the boxes 601, 602 and 603 must be able to move relative to each other according to travels corresponding to the travels to be imparted to the rules and supporting stems.
In particular, figure 26 is a schematic vertical section view of the apparatus 1000, examined on the plane A-A of figure 27. Figure 27 is a schematic vertical section view of the apparatus 1000, examined on the plane B-B of figure 26. These figures show that in this case the box 601 is stationary and the boxes 602 and 603 are movable vertically with respect to the box 601, in order to orient the sockets 2 in space as desired. In fact the boxes 602 and 603 are combined with corresponding actuators 6.
The cassettes are provided with metal rods, respectively 610, 620 and 630, on which the stem-holding rules 100, 200 and 300 are mounted. Preferably, in this version no actuators are provided for horizontally moving the stem-holding rules 100-300, but this movement - which is intended to compensate the variation of the centre-to-centre distance between the supporting stems 10-30 - is obtained by letting the stem-holding rules 100-300 free to translate by a very little travel on the respective rod 610, 620 or 630.
Certainly, the field technician will appreciate that the apparatus 1000 can be made of hundreds or thousands of supporting assemblies 1 in order to allow a corresponding number of stones S to be simultaneously machined, thereby favoring the productivity.

Claims

An apparatus (1000) for machining precious stones (S) or similar, particularly for lapping, grinding and polishing, comprising at least one lap (M) or an equivalent abrasive member, and at least one supporting assembly (1) to support the stones (S) to be machined, wherein the supporting assembly (1) comprises:
- a stone holding member (2), named socket, provided with a housing seat (3) to house a stone (S) to be machined; and wherein the supporting assembly (1) and the respective lap (M) are movable one with respect to another between a distal position, at which the stone (S) in the socket (2) does not interact with the lap (M), and a proximal position, at which the stone (S) in the socket (2) contacts the lap (M) to be either lapped, or ground or polished at a facet (F1, F2, F3),
characterized in that the supporting assembly (1) comprises:
- at least three supporting stems (10, 20, 30) to support the socket (2), each constrained to the socket (2) at a side opposite to the housing seat (3) of the stone (S) to be machined;
wherein the supporting stems (10-30) each extend along its own longitudinal axis, and
wherein each supporting stem (10-30) is constrained to the socket (2) so that to be able to be oriented, and
wherein, within the same supporting assembly (1), at least one first stem (10) and one second stem (20) are translatable in the two ways along their own longitudinal axis and the third stem (30) is stationary or else it is translatable too in the two ways along its own longitudinal axis, so that the instantaneous position adopted by the three supporting stems (10-30) defines univocally the orientation of the socket (2) and therefore of the stone (S) housed therein, with respect to the respective lap (M).
Apparatus (1000) according to claim 1, wherein the coupling among the supporting stems (10-30) and the socket (2) is of spherical type, i.e. every stem is provided with a spherical head (11, 21, 31) and the socket (2) is provided with a corresponding spherical seat (12, 22, 32), or vice versa, and/or the coupling is magnetic, so that the socket (2) can tilt with respect to the longitudinal axis of the supporting stem (10, 20, 30).
Apparatus (1000) according to claim 1 or claim 2, further comprising a stem-holding rule (100, 200, 300) for each supporting stem (10-30), wherein the supporting stems (10-30) are fixed to the respective stem-holding rule (100-300) extending transversely thereto, and wherein the movement of the supporting stems (10-30) is given by the respective stem-holding rule (100-300).
Apparatus (1000) according to claim 3, further comprising at least one supporting frame (600) to support the stem-holding rules (100-300), wherein:
- at least two supporting rules (100, 200) are movable in a transverse direction, i.e. moving closer and away one to/from another, with very little travels, and/or

- at least two supporting stems (10, 20) are flexible,
in order to compensate the variation of the centre-to-centre distance between the supporting stems (10-30), which occurs as the respective instantaneous longitudinal position changes.
Apparatus (1000) according to claim 3 or claim 4, comprising a plurality of supporting assemblies (1) for contemporaneously machining a corresponding number of stones (S), wherein the supporting assemblies (1) are arranged as aligned (5) on a single assembly of respective stem-holding rules (100-300), i.e. n first supporting stems (10) are fixed to, or integral with, the same first stem-holding rule (100), n second supporting stems (20) are fixed to, or integral with, the same second stem-holding rule (200) and n third supporting stems (30) are fixed to, or integral with, the same third stem-holding rule (300).
Apparatus (1000) according to claim 5, wherein the supporting assemblies (1) are arranged as determined by an array (500) comprising a plurality of lines (5) of supporting assemblies (1) placed side by side, and corresponding assemblies of stem-holding rules (100-300).
Apparatus (1000) according to claim 6, wherein every socket (2) of the supporting assemblies (1) is joined by an elastic blanket or protecting sheath (4) to protect from the dust, wherein the sheath (4) comprises a plurality of holes whose every single edge sealingly adheres to a corresponding socket (2).
Apparatus (1000) according to claim 7, wherein the volume underlying the protecting sheath (4) can be depressurized to guarantee the effectiveness of the coupling among the sockets (1) and the supporting stems (10-30), by avoiding their separation when the stone (S) interacts with the lap (M) and the friction generates a force tending to separate the sockets (2) from the stems (10-30).
Apparatus (1000) according to any one of claims 6-8, further comprising three supporting frames or boxes (601, 602, 603) and actuators (6), wherein every first stem-holding rule (100) of the array (500) is coupled with a first box (601), every second stem-holding rule (200) of the array (500) is coupled with a second box (602) and every third stem-holding rule (300) of the array (500) is coupled with a third box (603), wherein at least two (602, 603) of the three boxes are coupled with said actuators (6) driving the positioning thereof in a longitudinal direction so that the respective supporting stems make a corresponding longitudinal travel.
Apparatus (1000) according to claim 9, wherein the three boxes (601-603) are arranged as stacked one on another, or else they are arranged one inside another on the same level, and among the boxes (601-603) there is a clearance at least corresponding to the travels the stem-holding rules (100-300) must be able to cover.
Apparatus (1000) according to any one of the preceding claims, wherein every supporting assembly (1) is constrained to a movable arm (8) rotating with respect to the at least one lap (M).