Title of Invention: Multi-functional Work Centre for Cutting and Machining Plates of Stone, Marble, or, in General, Natural or Synthetic Stone Material, or Ceramic Material
Abstract: 
A numeric-control work centre can be used for carrying out cutting operations or grinding and/or milling operations on plates of stone, marble, or, in general, natural or synthetic stone material, or ceramic material. The work centre comprises at least one working head movable along at least two mutually orthogonal horizontal axes on a work surface. The work surface includes a rigid supporting board, which defines a first planar supporting surface, and a series of sacrificial elements rigidly connected to the rigid supporting board. The sacrificial elements are arranged in positions spaced apart from each other and define a second supporting surface located at a higher level than the first planar supporting surface, so that a cutting tool coupled to the working head engraves the sacrificial elements, without interfering with the supporting board during a cutting operation on a plate resting on the sacrificial elements, whichever is the path followed by the cutting tool. Between the sacrificial elements there remain free portions of the planar surface of the supporting board, so that they can be removably engaged by one or more blocks for supporting and holding the plate. These blocks project above the sacrificial elements and are adapted to define a third supporting surface, located at a higher level than the second supporting surface, for supporting and holding a plate during a milling or grinding operation on the plate.

Detailed Description: 

TECHNICAL FIELD
The present invention relates to numeric-control work centres for machining plates of stone material, whether natural or synthetic, or ceramic material. The invention relates in particular to a work centre of the type comprising a work surface and at least one working head that is movable on the work surface in at least two mutually orthogonal horizontal directions.
BACKGROUND
According to the most conventional technique, a plate to be worked, for example for producing a top for a kitchen or bathroom cabinet, is cut starting from a plate of large dimensions on a machine that usually is dedicated only to the cutting operation (typically a bridge-like milling machine), after which the semi-finished product obtained thereby is usually transferred into a work centre of the type referred to above, to undergo subsequent milling, grinding, or polishing machining operations.
In the machine dedicated to the cutting operation, the plate to be cut is supported on a “sacrificial” supporting surface, typically defined by a board or frame made of wood or other sacrificial material, in such a way that the disk blade used in the cutting operation, passing through the plate, cuts the sacrificial supporting surface without interfering with the top surface of the bench of the machine. When the cut semi-finished product is transferred onto the numeric-control work centre, it is supported and held in a position that is raised with respect to the bench of the work centre by means of a plurality of supporting and holding blocks, which can be positioned as desired on the top surface of the bench of the work centre in such a way that machining operations on the plate, such as grinding and polishing of the lateral peripheral surface of the plate, can be performed by the working head without interfering with the bench of the work centre. According to the most usual technique, these supporting blocks each make use of a bottom suction cup and a top suction cup, which can be activated by vacuum to maintain in a desired position each block on the bench of the work centre and to maintain in a fixed position the plate supported on the block. Once again according to the usual technique, each supporting block constitutes an independent unit, which can be positioned as desired on the bench of the work centre. Each block is connected by means of hoses to a source of vacuum or it incorporates a vacuum source (see EP 2 682 227 A1 in the name of the present applicant).
The present applicant has early realized of the problem of providing a multi-functional work centre that is able to sum up in one and the same machine the specific capabilities of a bridge milling machine and those of a work centre. For instance, in Italian patent IT 1 391 863, the present applicant has proposed a work centre provided with a removable sacrificial supporting surface, which has a structure similar to that of a roller shutter, and which can be displaced between an operative position extended over the bench of the machine, when the work centre is to be used for carrying out cutting operations, and an inoperative rolled-up condition, where the bench of the work centre is left free for positioning thereon suction-cup supporting blocks adapted to receive thereon a plate that is to undergo milling or grinding machining operations. A further solution for a work centre with a removable sacrificial supporting surface has formed the subject of Italian patent IT 1 416 728 filed in the name of the present applicant. The aforesaid known solutions, however, lead to a relatively complicated structure and arrangement, which are not always justified.
Document No. DE 38 39 150 C1 describes a numeric-control work centre for machining plates of stone, marble, or, in general, natural or synthetic stone material, or ceramic material, comprising:
a work surface; and
at least one working head movable on the work surface in at least two mutually orthogonal horizontal directions, wherein the working head can be coupled either to a tool for performing grinding or milling machining operations on the plate or to a tool for cutting the plate,
wherein said work surface includes:
a rigid supporting board, defining a first planar supporting surface; and
a series of elements for supporting a plate during a cutting operation, said elements being rigidly connected to said rigid supporting board and defining a second supporting surface located at a higher level than said first planar supporting surface of said supporting board, so that a cutting tool coupled to said at least one working head can carry out a cutting operation on a plate resting on said plate-supporting elements, without interfering with the supporting board,
said machine including a third supporting surface located at a higher level than said second supporting surface, for supporting and holding a plate during a grinding or milling operation performed on the plate by using a tool coupled to said working head and suitable for performing grinding or milling machining operations on the plate.
As a result, the above known work centre is able to carry out both cutting operations and grinding or milling machining operations. However, it does not make use of sacrificial elements, and the cutting operations are considerably limited by the fact that the cutting tool can move with respect to the work surface only along orthogonal lines, within the free spaces between the elements that support the plate during the cutting operation.
SUMMARY
The object of the present invention is to provide a multi-functional work centre that can be used both for carrying out cutting operations and for carrying out grinding and/or milling operations on the plate, while having a simple and low-cost structure and without posing any limitations on the path that the cutting tool can follow in carrying out a cutting operation.
With a view to achieving the aforesaid object, the subject of the invention is a numeric-control work centre for machining plates of stone, marble, or, in general, natural or synthetic stone material, or ceramic material, comprising:
a work surface; and
at least one working head movable on the work surface in at least two mutually orthogonal horizontal directions, wherein the working head can be coupled either to a tool for performing grinding and/or milling machining operations on the plate or to a tool for cutting the plate,
wherein said work surface includes:
a rigid supporting board, defining a first planar supporting surface; and
a series of elements for supporting a plate during a cutting operation, said elements being rigidly connected to said rigid supporting board and defining a second supporting surface located at a higher level than said first planar supporting surface of said supporting board so that a cutting tool coupled to said at least one working head can carry out a cutting operation on a plate resting on said plate-supporting elements without interfering with the supporting board,
said machine including a third supporting surface located at a higher level than said second supporting surface, for supporting and holding a plate during a grinding and/or milling operation on the plate performed by using a tool coupled to said working head and suitable for grinding or milling machining operations on the plate,
said work centre being characterized in that:
said elements for supporting the plate during a cutting operation are rigid sacrificial elements secured to the work surface and made of a sacrificial material, such as wood or the like, such that a cutting tool used in the cutting operation can pass through the plate and also engrave the sacrificial elements without interfering with the work surface of the machine, so that the cutting tool can be guided according to any path on the work surface without being forced to avoid interference with said sacrificial elements;
said third supporting surface is defined by a plurality of supporting blocks, each of which has a bottom suction cup that can be selectively activated for adhering to said work surface, and a top suction cup, which can be selectively activated for holding thereon a plate that is to undergo a milling or grinding operation;
defined between the sacrificial elements are free portions of said first planar surface of the supporting board, confined between said sacrificial elements and distributed throughout the entire extension of said first surface, so that they can be used for removably engaging said supporting blocks on said free portions; and
in the condition where said supporting blocks are engaged on respective free portions of the work surface, the top suction cups of the supporting blocks project above said sacrificial elements and define said third supporting surface.
In the preferred embodiment, the sacrificial elements are in the form of slats secured in any way (for example, bolted) on said supporting board and arranged so as to form at least one array of slats arranged spaced apart from one another. The distancing between the slats is greater than a horizontal dimension of the aforesaid supporting blocks in such a way as to leave free between the slats the aforesaid portions of surface suited to engagement of the supporting blocks. In an example, two arrays of parallel slats are provided arranged spaced apart from each other, along two different directions.
As clearly apparent from the foregoing description, the supporting board of the work centre according to the invention sums up in itself the characteristics of a sacrificial supporting surface and the characteristics of a supporting surface of the bench of a conventional work centre that is designed to receive thereon the blocks for supporting and holding a plate to be subjected to machining operations subsequent to a cutting operation.
To carry out a cutting operation, the plate is set resting on the sacrificial supporting surface, whereas to carry out operations of grinding or milling of the plate, the latter is set resting on one or more supporting and holding blocks, which are positioned as desired on free portions of the first supporting surface of the supporting board that are confined between sacrificial elements of the sacrificial supporting surface. During the cutting operation, the cutting tool is free to follow any desired path without the limitations of DE 38 39 150 C1.
The present invention is also directed to the method of use of the work centre described above.



BRIEF DESCRIPTION OF THE DRAWINGS
Further characteristics and advantages of the invention will appear from the following description with reference to the annexed drawings, which are provided purely by way of non-limiting example and in which:
FIG. 1 is a front perspective view of an examplary embodiment of a work centre according to the invention, illustrated during execution of an cutting operation on a plate arranged on the sacrificial supporting surface of the work centre;
FIG. 2 shows the same work centre as that of FIG. 1 during execution of a grinding operation on the peripheral lateral surface of a plate, where the plate is held on suction-cup supporting blocks, which are arranged on the supporting board of the work centre, in free portions of the surface of the board that are confined between elements of the sacrificial supporting surface; and
FIGS. 3 and 4 are a cross-sectional perspective view and a cross-sectional view of a detail of the supporting board forming part of the work centre according to the invention, FIG. 4 also illustrating a plate positioned on the sacrificial supporting surface and a plate positioned on suction-cup supporting blocks that engage on the surface of the supporting board.



DETAILED DESCRIPTION
In FIGS. 1 and 2, the reference number 1 generally designates a numeric-control work centre according to the present invention. The work centre 1 comprises, in a way known per se, a stationary structure including a bench 2 defining a work surface generally designated by 3. On two opposite sides of the bench 2, the stationary structure of the machine includes a pair of side portions 4. The work centre 1 comprises one or more working heads H (in the illustrated example, a single working head H is provided) which, once again in a way known per se, is supported by a slide structure 6 that is movable in a vertical direction Z on a carriage 7. Once again according to the conventional technique, the carriage 7 is slidably mounted in the longitudinal direction X of a cross-member 8 that is movably mounted, in a gantry-like fashion, above the two side portions 4 in a horizontal direction Y orthogonal to the direction X. The movement of the carriage 7 along the cross-member 8 in the direction X, the movement of the cross-member 8 in the horizontal direction Y, and the movement of the slide 6 in the vertical direction Z are controlled by respective electric motors (not illustrated) controlled by an electronic control unit (not illustrated) according to any predetermined machining program.
The constructional details of all the components described above of the work centre are not illustrated herein since they can be made in any known way and do not fall, taken alone, within the scope of the present invention. Moreover, the deletion of these constructional details from the drawings renders the latter more readily and easily understandable.
Once again according to the conventional technique, the working head H is provided with a motor-driven spindle (not visible in the drawings) to which a working tool can be removably coupled.
Normally, in work centres of the type described herein, the working head can be coupled to a grinding tool or a milling tool, to carry out, for example, milling operations to obtain recesses or openings in the plate, or grinding operations to machine the peripheral lateral surface of the plate and the edge of one or more openings formed within the perimeter of the plate (when these are provided) or to carry out any other type of machining operation. In the case of the work centre according to the invention, the working head can also be coupled to a tool for cutting the plate, the tool being typically in the form of a diamond disk blade, designated by D in FIG. 1.
The exemplary embodiment illustrated herein has a single working head H. In this case, the working head H is designed to operate both with a cutting tool and with a grinding or milling tool. The work centre 1 is provided with a tool magazine (not visible in the drawings) on a side of the bench 2, where the working head can be positioned to carry out automatically a tool-change operation. However, the work centre according to the invention could also be provided with a number of working heads, in which case each working head can be dedicated just to cutting operations or just to milling and grinding operations, or else each of the working heads can be provided for carrying out both types of operations.
The work centre 1 is provided with a work surface 3 defined by a supporting board 10 (see FIGS. 3 and 4), the structure of which will be illustrated hereinafter. Purely by way of example, the supporting board 10 is illustrated in FIG. 3 as constituted by a plurality of modular elements 101 in the form of metal sectional elements, which are set alongside one another and define with their top surfaces a first planar and continuous supporting surface 11. Once again with reference to the specific example illustrated in FIG. 3, the metal sectional elements 101 have longitudinal sides with complementary sectional elements in such a way that these metal sectional elements 101 are slotted together and moreover define a plurality of longitudinal slots 102. Received and fixed by means of screws 12 (see FIG. 4) within the longitudinal slots 102 are a plurality of slats of wood 131, which are thus parallel to one another and set at a distance apart, constituting a first array of slats of a sacrificial supporting surface 13 carried by the supporting board 10. In the example illustrated, the slats 131 of the first array are directed parallel to the direction X of the machine. As may be seen in FIG. 3, the top surfaces of the metal sectional elements 101 that define the first supporting surface 11 also have transverse slots, received and blocked within which, for example, by means of screws, are portions of slats of wood 132 arranged orthogonal to the slats 131 of the first array. The portions of slats 132 define a second array of slats set parallel to one another and at a distance apart, orthogonal to the slats 131 of the first array. Both the slats 131 and the portions of slats 132 project above the first supporting surface 11 to define a second supporting surface 14, located at a higher level than the first supporting surface 11.
Of course, the supporting board 10 can have a structure of any type, the specific configuration described above here being provided purely by way of example. In particular, the material of the slats may be any other sacrificial material alternative to wood. The slats could also be arranged in two different, but not orthogonal, directions. In the work centre according to the invention, the plate to be worked is set resting on the second supporting plane 14 defined by the sacrificial supporting surface 13 that is constituted by the slats of wood 131, 132, when it is necessary to carry out a cutting operation, as illustrated in FIG. 1.
Once positioned on the sacrificial supporting surface 13 constituted by the slats of wood 131, 132, the plate remains stationary by gravity during the cutting operation, thanks also to the friction between the bottom surface of the plate and the surface of the slats of wood 131, 132.
During the cutting operation, the disk blade D traverses the plate L positioned on the sacrificial supporting surface 13 throughout the thickness of the plate and projects for a few tenths of millimeter underneath the plate L. In this way, the disk blade D can engrave the slats 131, 132 that it possibly finds along its path, without however interfering with the supporting surface 11 of the supporting board 10.
Once again with reference to the specific example illustrated, the sacrificial supporting surface 13 also includes one or more perimetral slats of wood 133 fixed to the periphery of the supporting board 10 by means of screws 15.
It is important for the structure of the sacrificial supporting surface 13 to be made up of sacrificial elements, such as the slats of wood 131, 132 arranged at a distance apart in such a way as to leave free wide portions of the aforesaid first supporting surface 11 (designated by 110 in FIGS. 2 and 3), confined between the sacrificial elements, which are designed to be removably engaged by blocks V (see FIGS. 2 and 3) for supporting and withholding the plate, which project above the sacrificial elements 131, 132 so as to define a third supporting surface 16 (see FIG. 4) located at a higher level than the second supporting surface 14 defined by the sacrificial supporting surface 13, for supporting and holding a plate L during a grinding or milling operation on the plate (FIG. 2).
With reference to FIG. 4 (where the modular elements 101 are illustrated only schematically), the blocks V are of the known type including a bottom suction cup V1, a top suction cup V2, and connectors V3, V4 for connecting the suction cups to a source of vacuum provided within the stationary structure of the machine. For this purpose, once again according to the conventional technique, the connectors V3, V4 are connected to the ends of hoses F, which are in turn connected to connectors R provided on the stationary structure of the machine. The present description of the supporting and holding blocks V is provided herein purely by way of example. Alternatively, these blocks may be made in accordance with a known technique developed by the present applicant, according to which each block is provided with an autonomous vacuum source (see document No. EP 2 682 227 A1).
Whatever the structure and configuration of the blocks V, the latter are independent units that can be positioned as desired by the operator in the areas 110 free from slats 131, 132 according to the dimensions and shape of the plate L to be machined. Once the blocks V have been positioned, their bottom suction cups V1 are activated for fixing the blocks themselves to the first supporting surface 11. The plate L is then positioned on the blocks V, and the top suction cups V2 are then activated for holding the plate on the blocks. Once the plate has thus been held in a position raised both with respect to the sacrificial supporting surface 13 and with respect to the supporting surface 11, the working head H can be operated, after associating thereto, for example, a grinding tool G (FIG. 2) having a vertical axis, in such a way as to carry out a grinding machining operation on the peripheral lateral surface of the plate L, or any further necessary machining operation, for example, milling operations required to obtain recesses or openings in the plate L, by using a milling tool.
As is clearly apparent from the foregoing description, the basic idea forming the subject of the present invention consists in providing a work centre with a work surface that can be used both as a sacrificial supporting surface during a cutting operation and as a surface for arranging thereon blocks for supporting the plate during a grinding and/or milling operation on the plate. This is obtained by providing a supporting board, on which the sacrificial elements are arranged and configured in such a way that, on the one hand, an adequate support thereon is guaranteed for the plate that is to undergo a cutting operation and, on the other hand, there are left free portions of the supporting surface of the supporting board that are confined between the sacrificial elements and are distributed on the entire extension of the board, on which the blocks for supporting the plate that is to undergo a grinding and/or milling operation can be engaged. For this purpose, the distancing between the slats 131, 132 of each array is greater than a horizontal dimension of the suction-cup blocks V. In the case of blocks of a cylindrical shape, the aforesaid distancing is in any case greater than the maximum diameter of the blocks V.
Thanks to this simple arrangement, the user can have available a work centre that has a structure that is not more complex and/or more costly than a conventional work centre and that, notwithstanding this, is able to carry out both grinding or milling operations and cutting operations on plates of stone material. Elimination of the need for a machine dedicated just to cutting operations, and consequent elimination of the dead times necessary for transfer of a plate from a machine dedicated to the cutting operation to the numeric-control work centre that carries out subsequent machining operations on the plate, results in an immediate advantage, from the standpoint of productivity of the plant, overall costs of production, and space occupied in the plant.
Naturally, without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to what is described and illustrated herein purely by way of example, without thereby departing from the scope of the present invention.



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