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Title:
ELECTRONICALLY-CONTROLLED APPARATUS FOR CUTTING AND MACHINING NATURAL OR SYNTHETIC STONE PLATES OR GLASS PLATES
Document Type and Number:
WIPO Patent Application WO/2019/021172
Kind Code:
A1
Abstract:
An electronically-controlled multi-functional work center can be used to machine plates of natural or synthetic stone or glass plates. The work center is configured to perform both the cutting operations on a plate (L1, L2) and the machining operations on the edges of the plate portions (L1 A, L1 B, L2A, L2B) obtained as a result of the cutting operation, without the need to arrange a sacrificial plane above the machine top to perform the cutting operation. The machine top (3) is provided with a plurality of supporting and holding units (8) mounted movable in a horizontal direction Y on respective support cross-members (9), which in turn are mounted movable on the machine top (3) in a direction X perpendicular to the direction Y. The electronic control unit (E) of the work center positions a plurality of supporting and holding units (8) selected to receive a plate (L1, L2) to be cut in such a way as to maintain them all on both sides of the cutting line (T). After performing a cutting operation, the plate portions (L1 A, L1 B, L2A, L2B), which have been subdivided from said plate (L1, L2), are separated by a movement along said second horizontal direction (X) of the cross-members (9) carrying some of said selected units (8) and/or a movement of at least some of said selected units along said first horizontal direction (Y). In this way, the machining head (7) of the work center can carry out the machining of the edges of the aforesaid plate portions (L1 A, L1 B, L2A, L2B) on the same machine top (3). In a variant, the supporting and holding units (8) are also provided with a vertical movement, which can be used to separate the cut plate portions.

Inventors:
BELLI, Marco (via della Meccanica 16, Chiusa Di Ginestreto, I-61122, IT)
FRONGIA, Marco (via della Meccanica 16, Chiusa Di Ginestreto, I-61122, IT)
GENNARI, Gianluca (via della Meccanica 16, Chiusa Di Ginestreto, I-61122, IT)
Application Number:
IB2018/055493
Publication Date:
January 31, 2019
Filing Date:
July 24, 2018
Export Citation:
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Assignee:
BIESSE S.P.A. (via della Meccanica 16, Chiusa Di Ginestreto, I-61122, IT)
International Classes:
B28D1/00; B23Q3/16; B28D1/04; B28D7/00; B28D7/04
Foreign References:
US5700117A1997-12-23
EP1270147A22003-01-02
EP2845840A12015-03-11
EP2682226A12014-01-08
EP2998088A12016-03-23
EP1591427A12005-11-02
Attorney, Agent or Firm:
NOTARO, Giancarlo (Buzzi, Notaro & Antonielli d'Oulxcorso Vittorio Emanuele I, 6 Torino, I-10123, IT)
Download PDF:
Claims:
CLAIMS

1. An electronically-controlled apparatus for machining natural or synthetic stone plates or glass plates, comprising:

- a supporting structure (2) defining a machine top (3) for receiving the plates to be machined,

- a machining head (7) movable above the machine top in at least two mutually orthogonal directions (X, Y, Z) and provided with a machining tool,

- an electronic control unit (E), programmable to control said machining head (7) according to a predetermined machining cycle,

- wherein said machine top (3) includes a plurality of units (8) for supporting and holding the plate to be machined, each supporting and holding unit (8) being switchable between an active holding condition and an inactive condition,

- wherein each of said supporting and holding units (8) is movable along a first horizontal direction (Y) over a respective support cross- member (9)

- wherein each cross-member (9) is movable on the machine top (3) in a second horizontal direction (X) perpendicular to said first horizontal direction (Y),

characterized in that said electronic control unit (E) is programmed to perform a machining cycle which includes the following operations:

- positioning a plurality of supporting and holding units (8) which are selected to receive a plate (L1 , L2) thereon, by arranging all selected units

(8) on the two sides of a cutting line (T), which must be followed when cutting said plate (L1 , L2),

- activating said supporting and holding units (8) in such a way as to clamp the plate (L1 , L2) thereon,

- providing said machining head (7) with a cutting tool (C) and controlling the machining head (7) for cutting said plate (L1 , L2) along said cutting line (T),

- maintaining said supporting and holding units (8) in the active holding condition and spacing apart the plate portions (L1 A, L1 B, L2A, L2B) from each other, which have been subdivided from said plate (L1 , L2), by means of:

- a movement along said second horizontal direction (X) of the cross-members (9) carrying at least some of said selected units (8), and/or

- a movement of at least some of said selected units along said first horizontal direction (Y),

- providing said machining head (7) with a tool (G) for machining the edges of said plate portions, and controlling the machining head (7) for machining the edges of said plate portions, while maintaining said selected supporting and holding units (8) active,

whereby said apparatus is able to perform both the plate (L1 , L2)- cutting operations and machining operations of the edges of the plate portions (L1 A, L1 B, L2A, L2B) obtained as a result of the cutting operation, without the need to arrange a sacrificial plane above the machine top to perform a cutting operation.

2. An apparatus according to claim 1 , characterized in that each of said cross-members (9) is provided with a belt conveyor system (90), movable between an inoperative lowered position and an operative raised position, for loading the plates (L1 , L2) to be machined onto the machine top (3) and for unloading the machined plate portions (L1 A, L1 B, L2A, L2B) from the machine top (3).

3. An apparatus according to claim 1 , characterized in that the machine top (3) is provided with at least two machining areas (Z1 , Z2) each of which can receive a respective plate (L1 , L2) in such a way that the loading and unloading operations of a plate and the operation for spacing apart the plate portions (L1 A, L1 B, L2A, L2B), obtained as a result of a cutting operation, can be performed in each of the two machining areas (Z1 , Z2), while the machining head (7) is operative in the other machining area to perform a cutting operation or a machining operation of the edges of the plate portions obtained as a result of the cutting operation.

4. An apparatus according to claim 1 , characterized in that said apparatus is a work center of the type comprising:

- two side structures (4) arranged on both sides of the machine top (3), - a gantry-like bridge (5) guided over the two side structures (4), along the horizontal direction Y, perpendicular to the horizontal direction X of the gantry-like bridge (5),

- a carriage (6) movable in said horizontal direction (X) on the gantry-like bridge (5),

- said machining head (7) being mounted on the carriage (6) in a movable manner along a vertical direction Z.

5. An apparatus according to claim 4, characterized in that the aforesaid supporting cross-members (9) are parallel to the movement direction Y of the gantry-like bridge (5) and are movable in a direction parallel to the longitudinal direction X of the gantry-like bridge (5).

6. An apparatus according to claim 1 , characterized in that each of said cross-members (9) carries an electric motor (16) for driving the movement of the cross-member (9) along said second horizontal direction (X),and at least one pinion (14) driven by said electric motor (16) and meshing with a stationary rack (13) located adjacent to the machine top (3).

7. An apparatus according to claim 1 , characterized in that each supporting and holding unit (8) is carried by a slide (19) slidably mounted on the respective cross-member (9) and provided with a gripping member (86) configured to engage a run of a motorized endless belt (20), carried by the cross-member (9), to actuate the movement of said unit (8) along the cross-member.

8. An apparatus according to claim 7, characterized in that each supporting and holding unit (8) comprises a suction gripping device (80) connected to a depression source.

9. An apparatus according to claim 1 , characterized in that at least some of said supporting and holding units (8) are also movable in the vertical direction (Z), and in that the electronic control unit (E) is programmed for controlling the vertical movement of some of said supporting and holding units (8) in order to space apart a cut plate portion from the remaining plate portion.

10. A method for machining plates of natural or synthetic stone or glass plates with the aid of the apparatus of claim 1 , comprising the steps of: - positioning a plurality of supporting and holding units (8), which are selected to receive a plate (L1 , L2) thereon, by arranging all the cross- members (9) carrying said selected units (8) on the two sides of a cutting line (T), which must be followed when cutting said plate,

- activating said selected supporting and holding units (8) in such a way as to clamp the plate (L1 , L2) thereon,

- providing said machining head (7) with a cutting tool (C) and controlling the machining head (7) for cutting said plate (L1 , L2) along said cutting line (T),

- maintaining said supporting and holding units (8) in their active clamping condition and spacing apart the plate portions (L1 A, L1 B, L2A, L2B) ) from each other, which have been subdivided from said plate (L1 , L2), by means of:

- a movement along said second horizontal direction (X) of the cross-members (9) carrying at least some of said selected units (8), and/or

- a movement of at least some of said selected units along said first horizontal direction (Y),

- providing said machining head (7) with a tool (G) for machining the edges of said plate portions (L1 A, L1 B, L2A, L2B), and controlling the machining head (7) for machining the edges of said plate portions, while maintaining said selected supporting and holding units (8) active.

11. A method according to claim 10, characterized in that at least some of said supporting and holding units (8) are also movable in the vertical direction (Z), and in that said method comprises the step of controlling the vertical movement of some of said supporting and holding units (8) in order to space apart a cut plate portion from the remaining portion of the plate.

12. A method according to claim 1 1 , characterized in that the cutting operation is carried out along a closed line, identifying the perimeter of a shaped plate portion or the perimeter of an opening to be formed in the plate, in that after the cutting operation, some of said supporting and holding units are moved vertically to separate the cut plate portion from the machining waste and in that a finishing machining operation is then performed on the cut edge.

13. A method according to claim 10, wherein the aforesaid machine top (3) is provided with at least two machining areas (Z1 , Z2), characterized in that the loading and unloading of the plates above one of said machining areas (Z1 , Z2) and the spacing operation of the plate portions (L1 A, L1 B, L2A, L2B), obtained following a cutting operation, are performed in each of said machining areas (Z1 , Z2) while the machining head (7) is operative in the other machining area (Z1 , Z2) to perform a cutting operation or a machining operation on the edges of the plate portions (L1 A, L1 B, L2A, L2B) obtained as a result of the cutting operation.

Description:
"An electronically-controlled apparatus for cutting and machining natural or synthetic stone plates or glass plates"

****

TEXT OF THE DESCRIPTION

Field of the invention

The present invention relates to electronically-controlled apparatuses for machining natural or synthetic stone plates or glass plates, of the type comprising:

- a supporting structure defining a machine top for receiving the plates to be machined,

- a machining head movable above the machine top in at least two mutually orthogonal directions and provided with a machining tool,

- an electronic control unit, programmable to control said machining head according to a predetermined machining cycle,

- wherein said machine top includes a plurality of units for supporting and holding the plate to be machined, each supporting and holding unit being switchable between an active holding condition and an inactive condition,

- wherein each of said supporting and holding units is movable along a first horizontal direction over a respective support cross-member, and

- wherein each supporting cross-member is movable on the machine top in a second horizontal direction perpendicular to said first horizontal direction.

Apparatuses of the type indicated above, for example, are described in documents US-A-5 700 1 17, EP 1 270 147 A2 and IT 255 691 U (the latter document is by the same Applicant).

The invention relates, in particular, to electronically-controlled multifunctional work centers, for machining stone plates or glass plates, of the type comprising a supporting structure including two side structures arranged on the two sides of the machine top on which a gantry-like bridge is guided, movable along a horizontal direction X of the gantry-like bridge, and in which a carriage carrying the aforesaid machining head is mounted on the gantry-like bridge so that it is movable in the aforesaid horizontal direction X, the machining head being - in turn - movable in a vertical direction Z with respect to said carriage.

The work centers of the type indicated above are used successfully to perform the machining of the edges of semi-finished plates previously obtained by cutting operations starting from larger plates, in a completely automatic manner, with high productivity and high flexibility of use.

According to the conventional technique, the aforesaid cutting operation is performed on a dedicated machine, after which each plate obtained following the subdivision of the starting plate is transferred to a work center of the type described above, to proceed with the machining of the edges of the plate. It is clear that this mode of operation is economically costly, as it requires the provision of two different machines, it involves the employment of a large space in the production plant, and it does not allow a high productivity because of dead times due to the need to transfer plates from one machine to another.

In order to propose a work center that can be used both for performing the cutting operations and for performing the machining operations of the edges of the plates, the Applicant has already proposed - in the documents IT-B-1 391 863 and IT-A-TO 2013 215 - work centers equipped with a sacrificial machine top, configured for implementing cutting operations, temporarily overlapping on a main machine top. After carrying out a cutting operation, the sacrificial machine top is removed, and the plates obtained following the cutting operation are positioned on the main machine top, by means of a suction holding unit, in order to perform the machining operation of the edges. These solutions make it possible to perform both the cutting and the machining of the edges using the same machine, but they are not always easily adoptable, due to the relative complexity and resulting elevated cost of the apparatus.

Object of the invention

The object of the present invention is, therefore, to provide an apparatus for machining plates of natural or synthetic stone material, or glass plates, which is able to perform both a cutting operation of a plate and a machining operation of the edges of the plates obtained following the cutting operation.

A further object of the invention is to achieve the aforesaid objective with an apparatus that has a relatively simple structure and without appreciable cost increases, which - at the same time - allows a higher productivity.

Summary of the invention

In view of achieving the aforesaid objects, the invention relates to an electronically-controlled apparatus of the type indicated at the beginning of the present description, and further characterized in that the electronic control unit of the apparatus is programmed to perform a work cycle that includes the following operations:

- positioning a plurality of selected supporting and holding units, for receiving a plate thereon, by arranging all the selected units on the two sides of a theoretical cutting line, which must be followed when cutting said plate,

- activating said selected supporting and holding units in such a way as to clamp the plate thereon,

- providing said machining head with a cutting tool and controlling the machining head for cutting said plate along said theoretical cutting line,

- maintaining said selected supporting and holding units in their active clamping condition and spacing apart the plate portions from each other, which have been subdivided from said plate, by means of:

- a movement along said second horizontal direction (X) of the cross-members (9) carrying at least some of said selected units (8), and/or

- a movement of at least some of said selected units along said first horizontal direction (Y),

- providing said machining head with a tool for machining the edges of said plate portions, and controlling the machining head for machining the edges of said plate portions, while maintaining said selected supporting and holding units active,

whereby said apparatus is able to perform both the plate-cutting operations and the machining operations of the edges of the plate portions obtained as a result of the cutting operation, without the need to arrange a sacrificial plane above the machine top to perform the cutting operation.

Thanks to the provision of supporting and holding units movable along the aforesaid supporting cross-members along the aforesaid first horizontal direction, and thanks to the possibility of moving said supporting cross-members along the aforesaid second horizontal direction, the electronic control unit of the apparatus is able to position the aforesaid supporting and holding units, which are selected to receive the plate to be machined, keeping them all on the two sides of the cutting line. In this way, the electronic control unit is able to guarantee the rapid and precise positioning of the supporting and holding units in positions in order to exclude interference of these with the cutting tool. The cutting operation can, therefore, be carried out without requiring the provision of a sacrificial plane to support the plate to be cut. At the same time, an important aspect of the invention resides in having understood that the aforesaid movable cross-members and the supporting and holding units can be used advantageously to move the plate portions obtained by the cutting operation, and to move them away from each other, in order to be able to then carry out the machining of their edges. This represents a considerable advantage compared to the more traditional machines that are exclusively dedicated to cutting operations, wherein the movement of the plates is carried out with the aid of suction gripping units associated with the machining head of the machine. In the case of the invention, the cutting operations and the subsequent machining operations of the edges of the plate portions, obtained following the cutting operations, can be performed extremely efficiently and with reduced dead times, while always maintaining the supporting and holding units of the plate active both during the cutting operation and during the movement of the cut plate portions (obtained by a movement in the X direction of at least some of the cross- members that carry the supporting and holding units, and/or by a movement in the Y direction of at least some supporting and holding units on the respective cross-members) and during the machining of the edges of the plate portions after they have been moved away from each other.

In a preferred embodiment, the machine top of the apparatus according to the invention is provided with at least two spaced apart machining areas, each of which can receive a respective plate, in such a way that the loading and unloading operations of the plates, and the operation of spacing apart the plate portions after a cutting operation, can be carried out in each of the two machining areas, while the machining head is operative in the other machining area to perform a cutting operation or a machining operation of the edges of the plate portions obtained following the cutting operation.

In a variant, at least some of said supporting and holding units (8) are also movable in the vertical direction (Z), and in that the electronic control unit (E) is programmed for controlling the vertical movement of some of said supporting and holding units (8) in order to space apart a cut plate portion from the remaining plate portion.

Brief description of the figures

Further characteristics and advantages of the invention will become apparent from the description that follows with reference to the attached drawings, provided purely by way of non-limiting example, wherein:

Figure 1 illustrates a work center for cutting and machining stone or glass plates, according to a preferred embodiment of the present invention,

Figures 2-6 illustrate the work center of Figure 1 under different operating conditions,

Figures 7-9 are perspective views on an enlarged scale of the machine top of the work center of Figure 1 , in different operating conditions,

Figure 10 is a perspective view of a cross-member carrying a plurality of supporting and holding units,

Figure 1 1 is a side elevational view of the cross-member of Figure

10,

Figure 12 is an axonometric cross-sectional view of the cross- member of Figure 9, and

Figure 13 is a view, on an enlarged scale, of a detail of Figure 1 1 , In Figures 1 to 6, the reference number 1 indicates - in its entirety - a multi-functional work center according to a preferred form of the present invention, which is able to perform both the cutting operations on natural or synthetic stone plates, or on glass plates, and the machining operations of the edge of the plates portions obtained following the cutting operations.

The work center 1 comprises a supporting structure 2 defining a machine top 3 and two side structures 4 arranged on the two sides of the machine top 3 above which a gantry-like bridge 5 is guided, movable above the machine top 3 in a horizontal direction Y perpendicular to the horizontal direction X of the gantry-like bridge 5. On the gantry-like bridge 5, a carriage 6 is mounted movable in the direction X, on which a machining head 7 is mounted, movable along the vertical direction Z, including a spindle (not shown in the drawings) driven by an electric motor and carrying a machining tool. The movement of the carriage 6 along the X direction, the movement of the gantry-like bridge 5 along the direction Y, and the movement of the machining head 7 along the vertical direction Z are controlled by electric actuators, typically electric motors (not shown in the drawings). The electric actuators of the aforesaid movements along the directions X, Y, Z and the electric drive motor of the spindle of the machining head 7 are controlled by an electronic control unit E (illustrated schematically in Figure 1 only), which is programmed so as to carry out a predetermined work cycle on one or more plates to be machined.

The constructive details relative to the machining head 7, the spindle carried by said machining head, the machining tool, which is connected to the spindle in an uncouplable manner that allows it to be rapidly replaced, the carriage 6, the manner in which it is guided along the gantry-like bridge 5, and the manner in which the gantry-like bridge 5 is guided above the side structures 4, are neither described nor illustrated, since they can be made in any known manner, which will be readily apparent to those skilled in the art.

In accordance with the conventional technique, the work center 1 can be provided with a tool store (not illustrated) comprising a plurality of stations located adjacent to the machine top 3, at least some of which are occupied by respective tools, including both cutting tools and machining tools for the edges of the plates, for example, grinding tools. Still in accordance with the conventional technique, the control unit E positions the machining head 7 at the tool-carrying store whenever it is necessary to carry out an automatic replacement of the tool carried by the machining head. For this purpose, the machining head places a previously used tool in an empty location of the store, and then moves to a location of the store occupied by a new tool to perform automatic coupling of the spindle with the new tool.

The machine top 3 is equipped with a plurality of supporting and holding units 8. Each supporting and holding unit is movable in the direction Y on a respective supporting cross-member 9 which - in turn - is movable in the direction X on the machine top.

With reference to Figure 1 1 , each cross-member 9 comprises a structure including a pair of sliders 10 (one of which is visible on an enlarged scale in Figure 13) slidably mounted on guide brackets 1 1 carried by two longitudinal members 12 forming part of the supporting structure 2 of the work center. The longitudinal members 12 also carry two racks 13 parallel to each other and extending in the direction X, with which they engage two pinions 14 (see Figures 1 1 and 13) which are carried at the end of a transverse shaft 15 rotatably mounted on the structure of the cross-member 9, and positioned below it, and rotated by an electric motor

16, by means of a gearbox and a transmission belt 17.

The actuation of the electric motor 16 causes the rotation of the shaft 15 and the consequent movement of the cross-member 9 along the direction X above the machine top 3, following the rolling of the pinions 14 above the racks 13.

The aforementioned transmission for actuating the movement of each cross-member 9 along the direction X is, of course, associated with means of any known type suitable for sensing the position of the cross- member 9 along the direction X, so as to allow the electronic control unit E of the work center to check the position of each cross-member 9 along the

X direction.

With reference also to Figures 10 and 12, each cross-member 9 comprises a guide bracket 18 on which sliding slides 19 are mounted, each carrying a respective reference and holding unit 8. With reference, in particular, to Figure 12, each reference and holding unit 8 has, in the embodiment illustrated here, an upper end provided with a suction gripping device 80, of any known type, which can be operated by means of depression. The suction device 80 is configured to receive a plate to be machined thereon, so as to define a sealed chamber between a lower surface of the plate and the upper surface of the device 80. This chamber then communicates with a depression source by means of a duct (not illustrated) formed in the body 81 of the suction device 80, as well as by means of a duct 82 formed in the body of the respective slide 19. As seen in Figure 12, the duct 82 terminates in a connecting member 83 for connection to a flexible tube 84 arranged within the cross-member structure 9, which ensures that the communication of each suction device 80 is maintained with a remote and stationary vacuum source (not visible in the drawings) whatever the position of each slide 19 along the cross- member 9. In the same way, connection means are provided by means of flexible tubing, which ensure the aforesaid communication of the suction devices 80 with the stationary depression source, regardless of the position of each cross-member 9 along the machine top 3.

As an alternative to the solution described above, the holding units 8 could also be produced according to the disclosures of the documents EP 2 682 226 A1 and EP 2 682 227 A1 by the same Applicant, in which each unit is equipped with an autonomous and independent depression source.

As can be seen in Figure 10, inside the structure of each cross- member 9, an endless belt 20 is arranged, which is engaged on two vertical axis pulleys 21 (only one of which is visible in Figure 10), arranged at the ends of the structure of the cross-member 9. As can be seen in Figure 10, one of the pulleys 21 is driven into rotation by an electric motor 22 supported by the structure of the cross-member 9.

Each slide 19 carrying a respective supporting and holding unit 8 is provided with an actuator device 85 of any known type (Figure 12), which can be activated to cause engagement of a gripping member 86 over a run of the endless belt 20, so as to force the respective slide 19 to follow the run of the belt 20 in its movement. In this way, actuation of the gearmotor assembly 22 causes a movement of a supporting and holding unit 8 leading to activation of the respective actuator 84. The constructive details of this gripping member and of the respective actuator are not described here, since they are of a type known per se. Of course, even in this case, means are provided - of any known type - configured to detect the position of each slide 19 along the cross-member 9, in order to allow the electronic control unit E of the work center to move and position each reference and holding unit 8 along the respective cross-member 9, in any required manner.

The drawings do not illustrate the constructive details relative to the electrical connection for powering the electric motors 16, 22, which are produced by means of flexible conductors which leave the cross-members 9 free to move along the direction X on the machine top 3, and give each supporting and holding unit 8 the possibility of moving in the direction Y along the respective cross-member 9. Each slide 19 is also provided with a braking system of any known type, which is configured to clamp the slide 19 in any required position.

Referring again to Figure 1 , the preferred embodiment of the work center according to the invention provides two rows of cross-members 9 arranged so as to define two machining areas Z1 , Z2 adjacent to each other on the machine top 3.

Figure 2 shows an initial step of a possible work cycle of the work center 1 . In this step, two semi-finished plates L1 , L2, for example, of stone, or of marble, or of glass, are fed above the two areas Z1 , Z2 of the machine top 3.

In the illustrated example, each cross-member 9 is also provided with a respective belt conveyor system 90, which can be moved vertically between an operative raised position and an inoperative lowered position. In the condition illustrated in Figure 2, belt conveyor systems are raised and active, to allow the plates L1 , L2 to advance in the direction Y. Figure 3 shows the two plates L1 , L2 in the final position, at which the belt conveyor systems 90 are lowered so that the plates L1 , L2 are received over the supporting and holding units 8.

The following description refers to the case of a cutting operation to be performed along a line parallel to the direction Y.

A plurality of selected units 8 are activated to hold the plates L1 , L2 above them. Before this activation, the electronic control unit E of the machine positions the cross-members 9 in such a way as to ensure that they are all arranged on the two sides of the cutting line, for the subsequent cutting operation of the plates L1 , L2, so as to ensure that interference of the cross-members 9 with the cutting tools does not occur.

Figure 4 shows the step in which the machining head 7, provided with a disc-cutting tool C, operates on the plate L1 in such a way as to make a cut along a line T. As indicated, the cutting line T corresponds to a predetermined cutting line, parallel to the direction Y that the electronic control unit E takes into account to ensure that the cross-members 9 avoid any interference with the cutting blade T. Thanks to this arrangement, the cutting operation can be performed on the work center according to the invention, without any need to provide a sacrificial plane above the machine top 3.

Figure 5 shows the machining head 7 which has moved into the working area Z2 in order to perform the cutting operation above the plate L2. Of course, the cutting operations illustrated in Figures 4 and 5 are carried out with the supporting and holding units 8 active, so as to keep the plates L1 , L2 held and in position.

As can be seen in Figure 5, while the machining head 7 performs the cutting operation of the plate L2 along the line T, the two plate portions L1 A, L1 B, from which the plate L1 has been subdivided, are spaced apart while maintaining the respective supporting and holding units 8 in their active condition, and moving the cross-members 9 carrying one of the two portions L1 A, L1 B along the X direction, or moving the cross-members carrying both the plate portions L1 A, L1 B in opposite directions, always parallel to the direction X.

As can be seen, the separating operation of the two plates L1 A, L1 B is performed in a "masked" time without affecting the productivity of the machine, while performing the cutting operations in the machining area Z2.

Figure 6 shows the subsequent step in which the machining head 7 returns above the machining area Z1 after having replaced the previously used cutting tool with a grinding tool G suitable for machining the edge of the plate portions L1 A, L1 B. This operation is carried out while in the area Z2, the two plate portions L2A, L2B generated by the previous cutting operation of the plate L2 are moved away from each other, similarly to that illustrated in Figure 5 for the area Z1 . Also in this case, therefore, the dead time necessary for separating the two plate portions L2A, L2B is not detrimental to the productivity of the machine, since in the meantime, the machining head 7 performs the machining of the edges of the plate portions L1 A, L1 B in the machining area Z1 . The same can apply to the loading and unloading operations of the plates in each machining area, which can be carried out while the machining head is operative in the other machining area. Figure 7 shows - on an enlarged scale - an example of the use of the work center according to the invention, wherein a plate L1 is positioned above a part of the supporting and holding units 8 arranged along each cross-member 9 that is in the machining area Z1 . In the case of the example illustrated in Figure 7, the cross-members 9 do not have belt conveyor systems for loading and unloading the plates, which in this case must be carried out manually.

Figure 8 shows the two plate portions L1 A, L1 B after their separation, by means of moving at least some cross-members 9 in the X direction.

Figure 9 illustrates the same condition as in Figure 8 in the machining area Z1 and also illustrates the machining area Z2, with a plate L2 which has yet to be cut.

In the case of a cutting operation to be carried out along a line parallel to the X direction, suction units arranged on both sides of the cutting line are selected. After cutting, at least some of these suction units are moved along the respective cross-members 9, in order to space apart the two portions into which the plate has been subdivided from each other. However, it is also possible to provide cutting operations along diagonal lines, inclined both with respect to the X direction and with respect to the Y direction. In this case, the separation of the plate portions after cutting can be obtained either by a movement in the X direction of at least some the cross-members carrying the supporting and holding units, or by a movement in the Y direction of at least some supporting and holding units on the respective cross-members, or by both the aforesaid movements. Whatever the chosen solution, it is of course necessary to select the different suction units which retain different portions in which the plate is cut in such a way that these suction portions are able to move them relative to each other by a movement of the cross-members that carry them and/or a movement of the suction units with respect to the cross- members.

Of course, the electronic control unit of the machine can be programmed to perform cutting operations which define even more than two plate portions in the original plate, in which case, the different plate portions thus generated can be separated from each other by the movement of some of the cross-members along X and/or some of the suction units along Y.

According to an additional characteristic, the supporting and holding units (for example with a suction device) can be provided with a possibility of vertical movement (in the Z direction).

This last characteristic is useful when performing a cutting operation along a closed line, identifying the perimeter of a portion of a shaped plate or the perimeter of an opening to be formed in the finished plate. Once the cut has been made, it is possible to automatically remove the waste by means of a vertical movement in Z of the supporting and holding units, after which the finishing operation of the peripheral edge of the shaped plate portion, obtained with the cut can be carried out.

As is evident from the above description, the work center according to the present invention has multiple advantages. First of all, it can be used to perform both the cutting operations and the machining operations of the edges of the plates obtained by means of the cutting operation. Secondly, this result is obtained with a relatively simple structure and without significant cost increases, at the same time allowing greater productivity, since it is not necessary to arrange a sacrificial plane above the machine top 3 each time a cutting operation needs to be performed. Furthermore, the work center according to the invention is able to reposition the plate portions obtained as a result of a cutting operation, in order to be able to perform the machining of the perimeter edge of each plate portion, in an extremely simple and completely automatic manner, with the aid of movable cross-members and supporting and holding units.

Of course, the embodiment which has been described herein is given purely by way of example. For example, the reference and holding units could be carried by cross-members that extend in the direction X and which are movable in the direction Y. Furthermore, the shape of the supporting and holding units could be of any other type. The same applies to the actuating systems of the cross-members 9 and the units 8.

Generally, the embodiments and constructive details may vary widely with respect to those described purely by way of example, without departing from the scope of the present invention.