EP2731762B1

EP2731762B1 - Tool-holder unit of a machine for machining block or slab materials, machine including such unit for machining block or slab materials

Info

Publication number: EP2731762B1
Application number: EP12748784.1A
Authority: EP
Inventors: Luigi Guazzoni
Original assignee: GMM SpA
Current assignee: GMM SpA
Priority date: 2011-07-12
Filing date: 2012-07-05
Publication date: 2018-01-24
Anticipated expiration: 2032-07-05
Also published as: PT2731762T; EP2731762A1; ITMI20111298A1; WO2013008154A1

Description

Background of the invention

The present invention relates to a tool-holder unit of a machine for machining block or slab materials, in particular, but not exclusively, stone materials, such as for example, marble and granite.
The invention also relates to a machine for machining block or slab materials including such a tool-holder unit and to a method for machining block or slab materials which may be carried out by means of such a machine.
The term "machining" is used herein to indicate any operation carried out on a piece of material (block or slab), such as for example cutting, drilling, squaring, shaping, and the like.

Prior art

Machines for machining block or slab materials, and in particular stone materials, essentially comprise a table which defines a working plane on which the block or slab to be machined is laid, a tool-holder unit to which a machining tool, for example a circular blade or a mill, is associated, a displacing apparatus of the tool-holder unit and a drive and control unit equipped with a suitable operator interface.
In the present description and in the attached claims, the term "displacing apparatus", is used to indicate an apparatus adapted to cause any movement of the tool-holder unit, be it by translation or by rotation.
The tool-holder unit has a plurality of supply lines connected thereto, for example an electrical line or a line for feeding a cooling fluid to the machining tool. The displacing apparatus is mounted on a horizontal bridge which rests on walls or other vertical supporting structures.
The bridge is mobile on the respective support structures and the displacing apparatus is mobile along the bridge. In this way, the displacing apparatus and the tool-holder unit can be moved parallel to the working plane along two axes X and Y perpendicular to each other. In turn, the displacing apparatus can move the tool-holder unit along a further direction of displacement Z perpendicular to the working plane. In order to be able to carry out machining operations along both the directions of displacement X and Y as well as along oblique directions, it is also foreseen to rotate the tool-holder unit about the axis Z, in practice the vertical axis, so as to present the piece of material to be machined (block or slab) to the machining tool according to different angles.
The machining operations which the piece of material is subjected to may comprise cutting the material by means of a circular blade, plus other kinds of machining operations (drilling, squaring, shaping, etc.) to be carried out by means of additional machining tools, such as drills and mills of different types and sizes.
Generally, these additional tools are mounted on suitable tool-holders, which are associated to the tool-holder unit of the aforementioned machine, carrying the circular blade, by means of a suitable coupling assembly.
In particular, the tool-holder unit comprises a spindle on which the circular blade is mounted and the aforementioned tool-holders (carrying the different additional tools) are removably coupled to a front free end of the aforementioned spindle.
To this end, in a known machine the tool-holder unit is in particular equipped with a mechanical coupling device provided with elements cooperating in abutment relationship to make the tool-holder and the spindle rotationally integral with each other, for example comprising a plurality of driving pegs and a corresponding plurality of peg housing seats, and provided with a magnet made in a tool-holder coupling element associated to the spindle and capable of adhering the tool-holder to the coupling element.
In this way, it is possible to arrange different additional tools, each mounted on a respective tool-holder, in a suitable storage device, for example substantially of the rack type, positioned close to the machine, so that these additional tools can be quickly assembled/disassembled from the tool-holder unit, according to the machining required to be carried out on the piece of material.
In more recent machines for machining block or slab materials, it has been thought of automating the assembling/disassembling operations of the aforementioned tool-holders on the tool-holder unit.
To this end, it is however necessary to equip the tool-holder unit with a suitable system for positioning and moving the spindle which allows to position in perfect alignment the elements cooperating in abutment relationship that form the aforementioned mechanical coupling device (for example the pegs with respect to the respective housing seats).
In machines with automated tool changing, this perfect alignment is achieved by means of a positioning system comprising suitable sensors of the angular position (for example of the encoder type) and suitable devices of the inverter type capable of rotating the spindle with millimetric precision, so as to allow the desired correct alignment of the elements cooperating in abutment relationship of the mechanical coupling device.
In practice, once the angular position sensors of the tool-holder unit have detected the position of the pegs of the tool-holder to be assembled (arranged with other tool-holders available on the aforementioned storage device), the inverter rotates the spindle very slowly until the pegs and the respective housing seats are brought into mutual alignment; thereafter, the coupling surfaces of the tool-holder and of the front free end of the spindle are brought closer to each other so as to adhere such surfaces by means of the action of the magnet foreseen in the tool-holder coupling element.
WO 2005/014252 A1 discloses a device provided with a circular blade for cutting slabs of marble, granite, glass or similar materials comprising numerical control means for a cutting head having a blade mobile within a cutting volume and means for handling the slabs in the cutting volume.
DE 44 44 496 A1 discloses an adaptor for the coupling of interchangeable tools, such as for example grinding or polishing discs, on a work tool equipped with a motor and with a drive shaft. The adapter comprises a base body which may be connected to the work tool and a tool-holder which may be coupled to the base body and to which a tool is fixed. The base body and the tool-holder have mechanical coupling elements capable of allowing a mutual connection by means of a shape coupling. According to DE 44 44 496 , a plurality of magnets having the same polarity are associated to the base body and a plurality of magnets having the same polarity but opposite to the previous one are associated to the tool-holder, so as to hold the base body and the tool-holder together by means of the magnetic attraction. A tool holder unit according to the preamble of claim 1 and a method for machining bloc or slab materials are knownfrom WO2011/145005A1 , which is an intermediate document pursuant to Article 54(3) EPC.
In order to couple the tool-holder with the base body of the adapter, it is therefore required to have a perfect alignment between the mechanical coupling elements, this both in order to ensure the shape coupling between base body and tool-holder and to ensure the consequent subsequent holding action of the magnets.

Summary of the invention

The Applicant has found that the machine for machining block or slab materials with an automated tool change structured in the way schematically described above does, however, have various drawbacks essentially related to the fact that the tool-holder unit and the machining machine which includes the same must necessarily be provided with a sophisticated and expensive system for positioning and moving the spindle, which system must be capable of detecting, with high precision, the position of the elements cooperating in abutment relationship of the mechanical coupling device (for example of the pegs or of other elements with a similar function) and then of rotating with the necessary precision the spindle until the elements of the mechanical coupling device are brought in a condition which allows the same of cooperating in abutment relationship (for example, by bringing the aforementioned housing seats into perfect alignment with the pegs themselves).
In addition to the manufacturing costs, such a positioning system necessarily involves very slow movements of the spindle, in particular in the final step of its rotation immediately prior to reaching the desired perfect alignment between the elements of the mechanical coupling device, with an undesired increase of the time needed to change a tool and to carry out a machining of the materials.
Entirely similar drawbacks limit the performance of the adapter for the coupling of interchangeable tools described by DE 44 44 496 since also in this case it is necessary to have, in the case of a complex machine such as a machine for machining block or slab materials, a sophisticated and expensive system for positioning and moving the spindle that is capable of detecting with high precision the position of the mechanical coupling elements which are provided for allowing a mutual connection by shape coupling between the base body connectable to the tool-holder unit and the tool-holder.
The Applicant has thus realised the possibility of overcoming the aforementioned drawbacks and, more specifically, the possibility of providing a tool-holder unit of a machine for machining block or slab materials and a machine that incorporates such a unit, by intervening on the structural and functional characteristics of the coupling assembly of the tool-holder to the spindle in such a way as to impart to such an assembly advantageous features of automatic self-centring of the elements which constitute the same.
More specifically, according to a first aspect, the present invention relates to a tool-holder unit of a machine for machining block or slab materials as defined in claim 1.
In particular, the invention relates to a tool-holder unit moveable above a working plane of said machine on which the block or slab material to be machined is laid, wherein the tool-holder unit comprises:

a spindle on which a circular blade is mounted, and
a coupling assembly for removably coupling a second machining tool to a front free end of the spindle, comprising: a tool-holder associated to the second machining tool and at least one mechanical coupling device provided with elements cooperating in abutment relationship to make the tool-holder and the spindle rotationally integral with each other,

at least two first magnets with north polarity and at least two second magnets with south polarity, associated to the front free end of the spindle and circumferentially arranged alternating with each other at said front free end,
at least two third magnets with south polarity and at least two fourth magnets with north polarity, associated to a free end of said tool-holder and circumferentially arranged alternating with each other at said free end of the tool-holder.

Advantageously, the coupling assembly of the tool-holder unit of the invention has automatic self-centring characteristics of the element which constitute the same, which characteristics greatly simplify the structure of the devices for positioning and moving the spindle and speed up the assembling/disassembling operations of the tool-holders on the tool-holder unit, overcoming the aforementioned drawbacks of the cited prior art.
Thanks to the features of the aforementioned coupling assembly, in fact, the elements cooperating in abutment relationship which form the mechanical coupling device (for example pegs extending from the tool-holder and respective housing seats formed in the spindle) are positioned in perfect mutual alignment very quickly and precisely by simply bringing the spindle close to the tool-holder.
The magnetic fields generated by the magnets with opposite polarities arranged next to each other and associated to the free end of the tool-holder and to the front free end of the spindle, in fact, cause a rotation of the tool-holder which brings into perfect mutual alignment both the magnets of opposite polarity associated to the spindle and to the tool-holder, and the elements cooperating in abutment relationship that form the mechanical coupling device (for example, the driving pegs and the respective housing seats associated to the free end of the tool-holder and to the front free end of the spindle).
In practice, as the spindle approaches, the tool-holder rotates about its longitudinal axis until the magnets of opposite polarity arranged alternating with each other and associated to the spindle and to the tool-holder are brought into mutual alignment, whereas a subsequent approaching movement between the spindle and the tool-holder causes the respective magnets having opposite polarity to adhere to each other, completing the coupling between the machining tool associated to the tool-holder and the spindle of the machine for machining the material.
At the same time, a perfect mutual alignment of the elements cooperating in abutment relationship which form the mechanical coupling device (for example, the driving pegs and the respective housing seats associated to the free end of the tool-holder and to the front free end of the spindle) is also achieved.
In this way, the assembling of the different tool-holders on the spindle is not only quick and simple, but is also obtained with a tool-holder unit which is mechanically simple and less expensive than the corresponding units of the prior art since the position sensors and the inverter described above are no longer necessary.
In addition, the tool-holder unit of the present invention also achieves improved characteristics of reliability since its operation in an automatic tool change is no longer subject to possible failures of the positioning sensors and of the inverter.
According to the invention, the circumferential alternation of the magnets at the front free end of the spindle and at the free end of the tool-holder can be achieved both by individually alternating the magnets of opposite polarity according to a north-south arrangement, or by alternating groups of magnets having opposite polarity, for example according to a north-north/south-south arrangement.
The specific arrangement of the circumferential alternation of the magnets and the number of magnets included in each of the aforementioned groups can be determined by a man skilled in the art as a function of the characteristics and of the overall number of magnets so as to achieve the desired automatic alignment between the elements which constitute the coupling assembly as illustrated in the present description.
In a preferred embodiment of the invention, the aforementioned first and second magnets are associated to a tool-holder coupling element associated to the front free end of the spindle. In this way, it is advantageously possible to use a spindle of substantially conventional type, having a diameter typically smaller than that of the tool-holder coupling element which is associated thereto (and on which the first and second magnets are arranged), with a consequent reduction of the manufacturing costs. According to an example, the tool-holder coupling element comprises a threaded cylindrical portion in screwing engagement in a corresponding cylindrical seat provided in the front free end of the spindle. This type of coupling between the tool-holder coupling element and the spindle has the advantage of being simple, cost-effective and efficient.
When the tool-holder coupling element is present, the aforementioned first and second magnets are preferably associated to a coupling flange of the tool-holder coupling element and the aforementioned third and fourth magnets are associated to a respective coupling flange of the tool-holder.
In this way, it is advantageously possible to arrange a suitable number of magnets along a circular crown defined between two inner circumferences of the flanges.
More preferably, the first magnets are circumferentially arranged alternating with the second magnets in the coupling flange of the tool-holder coupling element, and the third magnets are circumferentially arranged alternating with the fourth magnets in the respective coupling flange of the tool-holder.
In this way, it is advantageously possible to facilitate the achievement of the desired orientation of the tool-holder with respect to the spindle, reducing the amount of rotation of the tool-holder with respect to the spindle itself. According to an example, the number of each of said first, second, third and fourth magnets is comprised between three and six. In other words, the total number of magnets with opposite polarities associated to the front free end of the spindle or, if present, to the tool-holder coupling element associated to the front free end of the spindle or, respectively, associated to the free end of the tool-holder is preferably comprised between 6 and 12. According to an example, the coupling assembly comprises 16 magnets, 8 of which are associated to the front free end of the spindle or, if present, to the tool-holder coupling element associated to the front free end of the spindle (4 with north polarity and, respectively, 4 with south polarity) and 8 of which are associated to the free end of the tool-holder (4 with north polarity and, respectively, 4 with south polarity).
In this way, it is advantageously possible to further facilitate the achievement in a short time of the desired orientation of the tool-holder with respect to the spindle by reducing the amount of rotation of the tool-holder with respect to the spindle itself as a function of the number of magnets.
Thus, for example, the maximum rotation of the tool-holder with respect to the spindle may have an angular value of 60° in the case of 6 magnets progressively reducing to 30° in the case of 12 magnets for each element of the coupling assembly.
Moreover, by increasing the total number of magnets it is advantageously possible to reduce the manufacturing costs of the tool-holder unit since it is possible to use magnets having a smaller size which are more easily procured on the market and have a significantly lower cost with respect to larger magnets.
Preferably, the first and the second magnets can be arranged in the front free end of the spindle or, if present, in the tool-holder coupling element associated to the front free end of the spindle according to a single annular array or, alternatively, according to a plurality of concentric annular arrays. Preferably, the magnets are in both cases circumferentially arranged at an equal distance from each other. According to an example, the magnets arranged in the radially innermost annular array can be circumferentially interposed with the magnets arranged in the radially outermost array(s).
In this way, it is advantageously possible to further facilitate the achievement of the desired orientation of the tool-holder with respect to the spindle by reducing the amount of rotation of the tool-holder with respect to the spindle itself as a function of the number of magnets and of the arrangement thereof. According to an example, the aforementioned preferred arrangements are also foreseen for the third and fourth magnets associated to the free end of the tool-holder achieving analogous advantageous technical effects.
Preferably, the aforementioned first, second, third and fourth magnets are substantially flush-mounted in the front free end of the spindle, or, if present, in the tool-holder coupling element associated to the front free end of the spindle and/or in the free end of the tool-holder.
In this way, it is possible to achieve an optimal adhesion between the elements which constitute the coupling assembly without the formation of gaps in which dust or other particulate material generated by the machining carried out on the material may be deposited.
Preferably, the coupling assembly of the tool-holder unit of the invention further comprises a frusto-conical guide, coaxially extending from the tool-holder, and a corresponding frusto-conical seat, formed in the front free end of the spindle or, if present, in the tool-holder coupling element associated to said front free end.
Advantageously, the frusto-conical guide and the corresponding frusto-conical seat allow to achieve a coupling with a perfect coaxiality between the tool-holder and the spindle (or between the tool-holder and the tool-holder coupling element). According to an example, the elements cooperating in abutment relationship of the mechanical coupling device of the coupling assembly comprise:

a plurality of driving pegs axially extending from one of the free end of the tool-holder and the front free end of the spindle, and
a corresponding plurality of seats for housing the driving pegs, formed in the other of the free end of the tool-holder and the front free end of the spindle.

In particular, the invention relates to a machine for machining block or slab materials, comprising a working plane on which the block or slab material to be machined is laid and a tool-holder unit according to any one of claims 1-7.
Preferably, such a machine for machining block or slab materials thus has, individually or in combination, all of the structural and functional characteristics discussed above with reference to the tool-holder unit of the first aspect of the invention and therefore possesses all of the aforementioned advantages.
In a particularly preferred embodiment, the machine of the invention further comprises a handling unit coupled to the tool-holder unit and provided with gripping means of the block or slab material to be machined, wherein the gripping means are mobile between a first non-operative position, distal with respect to the working plane, and a second operative position, proximal with respect to the working plane, the gripping means being rotatable between the first non-operative position and the second operative position.
In this way, the machine of the invention is advantageously capable both to carry out machining with the circular blade on the block or slab material and to carry out movements of the latter in a very quick and simple manner.
Advantageously, the gripping means are rotated in the second operative position to handle the block or slab material, and are rotated in the first operative position to allow the operation of the tool-holder unit. This feature allows to use, for the handling unit, the same system of spatial coordinates X, Y and Z of the tool-holder unit coupled to the same, and therefore allows to use the same displacing apparatus. A drive and control unit of the machine therefore uses just one system of coordinates for moving both the tool-holder unit, and the manipulator, avoiding a correlation of different reference systems, with obvious simplifications in the operation of the machine as a whole.
According to an example, the tool-holder unit is movable along two axes X and Y perpendicular to each other and parallel to the working plane, is movable along an axis Z perpendicular to the axes X and Y and is rotatable about an axis substantially perpendicular to the axis Z, whereas the gripping means are rotatable about an axis substantially perpendicular to the axis Z.
Moreover, the aforementioned machine according to the invention preferably comprises a displacing apparatus of the tool-holder unit and a support structure of the displacing apparatus and of the tool-holder unit above the working plane, the gripping means being integrally coupled to the tool-holder unit. Thus, the gripping means and the tool-holder unit rotate in an integral manner.
For the purposes of the present invention, the term "support structure" is used to identify a set of structural elements assembled to support the tool-holder unit and the corresponding displacing apparatus above the working plane. According to an example, the tool-holder unit is hinged in turn to the corresponding displacing apparatus and is rotatable between:

i) a first operative position, wherein the circular blade mounted on the spindle of the tool-holder unit can interact with the block or slab material being machined and the gripping means are in the corresponding first non-operative position, and
ii) a second operative position, wherein the second machining tool, if present, can interact with the block or slab material being machined, or wherein the gripping means are in the corresponding second operative position, in the absence of said second machining tool.

In this way, the machine achieves important characteristics of flexibility of use: the machine is in fact advantageously capable of carrying out working operations with the circular blade on the block or slab material, of carrying out working operations with the second machining tool if present or of carrying out movements of the block or slab material if the second machining tool is not associated to the tool-holder unit. According to an example, the rotation of said tool-holder unit is preferably comprised between 0° and 90°. According to an example of the machine, the tool-holder unit is rotatable about the axis Z. This feature allows to incline the tool with respect to the axes X and Y. According to an example, the aforementioned gripping means are of pneumatic type. According to an example, the aforementioned gripping means comprises at least one suction cup formed in a protective element of the circular blade or in a plate associated to a protective element of the circular blade, and the handling unit comprises one or more air suction ducts connected to the aforementioned at least one suction cup.
In both the aforementioned examples, each suction cup can for example be defined by a shaped gasket applied to the protective element of the circular blade, or else to the aforementioned plate associated to such a protective element, so as to circumscribe a corresponding surface portion thereof and the suction ducts are partially formed in the material of the protective element, or of the plate, and are open in the surface delimited by the gasket.
In both the aforementioned examples, moreover, the handling unit preferably comprises one or more on-off valves of the suction ducts. More preferably, such valves are solenoid valves that can be actuated by an external drive and control unit.
When the suction cups abut against the block or slab material being machined, in practice when the protective element, or the plate associated to such a protective element, rest on the block or slab material being machined, the gaskets are at least partially compressed against the surface of the block or slab material being machined; the opening of the on-off valves of the suction ducts allows to create a vacuum in the volume comprised between the block or slab material being machined and the protective element (or the plate), actually achieving a suction effect.
In this operating mode, a lifting movement of the gripping means and/or of the tool-holder unit along the axis Z causes a corresponding lifting movement of the block or slab material being machined, which can consequently be repositioned. The closing of the suction ducts causes the recovery of the pressure in the volume comprised between the block or slab material and the protective element (or the plate) and the consequent release of the block or slab material.
The machine can be provided with a proximity sensor or a limit switch, arranged on the gripping means or on the tool-holder unit, having the function of signalling when the gripping means or the tool-holder unit is at a predetermined distance from the block or slab material being machined. The signal generated by the sensor, suitably processed, can be used to prevent violent collisions of the gripping means or of the tool-holder unit against the material being machined.
In a third aspect thereof, the invention relates to a method for machining block or slab materials according to claim 10. In particular, the invention relates to a method for machining block or slab materials comprising the steps of:

a) arranging a block or slab material on a working plane,
b) moving a tool-holder unit, comprising a spindle on which a circular blade is mounted, above the working plane,
c) carrying out a cutting operation on said block or slab material by means of said circular blade,
d) rotating the tool-holder unit about an axis substantially parallel to the working plane,
e) removably coupling a second machining tool to a front free end of the spindle of the tool-holder unit by means of a coupling assembly comprising a tool-holder associated to the second machining tool,
f) carrying out an additional machining operation on said block or slab material by means of said second machining tool,

at least two first magnets with north polarity and at least two second magnets with south polarity, associated to said front free end of the spindle and circumferentially arranged alternating with each other at said front free end,
at least two third magnets with south polarity and at least two fourth magnets with north polarity, associated to a free end of said tool-holder and circumferentially arranged alternating with each other at said free end of the tool-holder, and

bringing the spindle close to the tool-holder,
orienting the elements cooperating in abutment relationship of the mechanical coupling device of the coupling assembly by means of a magnetic interaction between the magnets associated to the free end of the tool-holder and the magnets associated to the front free end of the spindle, and
magnetically associating the front free end of the spindle to the free end of the tool-holder.

Advantageously and as discussed above with reference to the tool-holder unit of the present invention, the method of the invention allows to associate the tool-holder to the front free end of the spindle in an extremely quick manner, with an automatic rotation of the tool-holder with respect to the spindle until a correct alignment is achieved of the corresponding magnets and of the elements cooperating in abutment relationship of the mechanical coupling device of the coupling assembly.
All this is achieved with a simplification of the devices for moving the spindle which no longer require the presence of position sensors and of the inverter as instead required by the tool-holder units and by the machining machines of the prior art.
Preferably, in order to carry out such a method for machining block or slab materials it is possible to use the tool-holder unit of the first aspect of the invention described above, having individually or in combination all the structural and functional features discussed above, with the corresponding aforementioned advantages.
Preferably, the magnetic interaction between the magnets with opposite polarities arranged next to each other and associated to the free end of the tool-holder and the magnets with opposite polarities arranged next to each other and associated to the front free end of the spindle induces a rotation of the tool-holder with respect to the spindle adapted to bring in a substantially aligned arrangement both the magnets of opposite polarity associated to the spindle and to the tool-holder, and the elements cooperating in abutment relationship of the mechanical coupling device of the coupling assembly.
In a preferred embodiment of the method of the invention, the elements cooperating in abutment relationship of the mechanical coupling device of the coupling assembly comprise:

a) a plurality of driving pegs axially extending from one of the free end of the tool-holder and the front free end of the spindle, and
b) a corresponding plurality of housing seats for the driving pegs, formed in the other of the free end of the tool-holder and the front free end of the spindle;

In a preferred embodiment, the machining method of the invention further comprises the step of storing a plurality of second machining tools and of tool-holders associated thereto in a substantially rack-type storage device provided with locking elements of the tool-holders.
In this way, it is advantageously possible to carry out a plurality of machining operations using different tools which may be coupled to the spindle of the tool-holder unit in an extremely quick and simple manner.
Preferably, the aforementioned coupling step e) is thus carried out by picking up a second machining tool from the substantially rack-type storage device by means of the coupling assembly.
In a further preferred embodiment, the machining method of the invention further comprises the step of

g) decoupling the second machining tool from the front free end of the spindle of the tool-holder unit by inserting the tool-holder in the substantially rack-type storage device along a lateral insertion path, and moving the spindle away from the storage device along a direction substantially perpendicular to the lateral insertion path.

In this way, it is advantageously possible to remove in a very quick and simple manner a tool-holder so as to associate a new tool to the spindle of the tool-holder unit or to stop machining.

Brief description of the drawings

Additional features and advantages of the present invention will become more clearly apparent from the following description of a preferred embodiment thereof, made with reference to the attached drawings, given for indicating and not limiting purposes. In such drawings:

Fig. 1 is a schematic perspective view of a preferred embodiment of a machine for machining block or slab materials according to the invention;
Fig. 2 is a schematic perspective view of a detail of the machine shown in Fig. 1, which illustrates a preferred embodiment of a tool-holder unit of the invention and of a displacing apparatus thereof, in a first configuration;
Fig. 3 is a schematic perspective view of a detail of the machine shown in Fig. 1, which illustrates a preferred embodiment of a tool-holder unit of the invention and of a displacing apparatus thereof, in a second configuration;
Fig. 4 is a schematic perspective view of a detail of the tool-holder unit shown in Fig. 2;
Fig. 5 is a schematic perspective view of a detail of the tool-holder unit shown in Fig. 4, which shows the front free end of the spindle of the tool-holder unit;
Fig. 6 is a schematic perspective view analogous to that of Fig. 5, which shows a tool-holder coupling element according to a preferred embodiment of the invention, associated to the front free end of the spindle of the tool-holder unit;
Fig. 7 is a schematic perspective view of the preferred embodiment of the tool-holder coupling element shown in Fig. 6;
Fig. 8 is a schematic perspective view of a preferred embodiment of the tool-holder to be coupled to the tool-holder coupling element shown in Fig. 7;
Fig. 9 is a schematic perspective view of an assembly obtained by coupling the tool-holder coupling element shown in Fig. 7 and the tool-holder shown in Fig. 8;
Fig. 10 is a schematic perspective view of the tool-holder coupling element shown in Fig. 7, made according to a different angle;
Fig. 11 is a schematic perspective view of a plug which may be associated to the tool-holder coupling element shown in Fig. 10;
Fig. 12 is a schematic perspective view of the tool-holder coupling element shown in Fig. 10 in the assembling position of the plug shown in Fig. 11.

Detailed description of a preferred embodiment of the invention

With initial reference to figure 1, a machine for machining block or slab materials, in particular, but not exclusively, stone materials, according to the invention is generally indicated at 100.
A table 101 is shown defining a working plane 102. The table can be stationary, such as in the illustrated example, or motorised and rotatable about a vertical rotation axis, not shown.
In general, the table 101 is not part of the machine 100; alternatively, the table 101 can be a component of the machine 100. The block or slab material to be machined is indicated with reference numeral 200.
In general the machine 100 comprises a tool-holder unit 10, a corresponding displacing apparatus 1 and a support structure 104.
The support structure 104 has the function of keeping the tool-holder unit 10 and the corresponding displacing apparatus 1 suspended above the working plane 102, on which the material 200 is positioned. In the embodiment shown in the attached figures, the support structure 104 comprises a bridge 105 which rests, at its ends, on walls 106 or other equivalent supporting structures, extending in a direction perpendicular to the bridge 105 itself. The support structure 104 thus comprises at least the elements 105 and 106.
The displacing apparatus 1 comprises a motorised trolley 2, adapted to move on the bridge 105 parallel to a longitudinal axis of the bridge 105 itself (i.e. along the direction indicated with X), and a shaft 3. At the lower end of the shaft 3 a fork-shaped body 13, to which the tool-holder unit 10 is fixedly connected, is provided and at the upper end of the same shaft 3 a reduction gear 4, preferably with zero clearance, is located. The displacing apparatus 1 thus comprises at least the components 2, 3, 13.
The shaft 3 is movable along its longitudinal axis Z - extending in a substantially vertical direction in the use configuration of the machine 100 - thanks to the presence of linear actuators 5 fixedly connected to the upper end of the shaft 3, for example fixedly connected at the reduction gear 4, and to the trolley 2. The apparatus 1 also has the function of guiding supply lines 6 towards the tool-holder unit 10.
The supply lines 6 preferably comprise at least one electrical supply line and at least one supply line of a fluid, for example water, intended to cool the machine tools of the tool-holder unit 10 during operation. Preferably, the shaft 3 is hollow and the supply lines 6 are housed in a corresponding inner cavity.
Preferably, the displacing apparatus 1 is also arranged to rotate the tool-holder unit 10 about the axis Z. Such a rotation, imparted by a motor through interposition of the reduction gear 4, is indicated by the arrow W.
The displacing apparatus 1 is movable along the bridge 105 and the latter is movable parallel to the direction of extension Y of the walls 106. The displacing apparatus 1, and along therewith the tool-holder unit 10, may therefore be moved parallel to the working plane 102 along two axes perpendicular to each other (directions X and Y) and, as explained above, may be moved parallel to the axis Z and rotated about this axis (rotation W).
A first machining tool, in the form of a circular blade 11, is associated to the tool-holder unit 10 to carry out cutting operations. In addition, a tool-holder 50 (Figs. 8, 9) for a second machining tool, schematically illustrated in Fig. 8 with reference numeral 28, for example a slot mill, a grinder, a drill bit, etc, may be removably coupled to the tool-holder unit 10.
The tool-holder 50 and the method of coupling to the tool-holder unit 10 according to a preferred embodiment of the present invention will be described hereinbelow with specific reference to Figs. 5-12.
With reference to Figs. 1-4, the tool-holder unit 10 essentially comprises a spindle 12, preferably actuated by an electric motor 17, such that the spindle 12 is also known in the field with the term of electro-spindle. The spindle 12 is capable of rotating the circular blade 11 associated thereto. Preferably, the spindle 12 is supported by the fork-shaped body 13 of the displacing apparatus 1 integral with the shaft 3.
In particular, the spindle 12 is rotatably supported by means of rotation pins 15 about a respective rotation axis E-E, substantially perpendicular to the vertical axis Z. In practice, the spindle 12 and the circular blade 11 can be tilted with respect to the fork-shaped body 13. In this way, the tool-holder unit 10 may rotate about the axis E-E (the fork-shaped body 13, on the other hand, does not rotate about the same axis E-E).
Preferably, the fork-shaped body 13 rotates integrally with the shaft 3 about the axis Z (rotation W). The tool-holder unit 10 thus preferably comprises at least the elements 11, 12, 14 and 17, but not the support body 13 which is part of the displacing apparatus 1.
In the preferred embodiment illustrated herein, the tool-holder unit 10 comprises a motor 14 adapted to move the spindle 12 about the rotation axis E-E to vary the angle of inclination of the spindle 12 with respect to the shaft 3. In this way, the circular blade 11 can be moved according to a further direction of rotation, indicated at R in the figures, to easily make, for example, inclined cuts or shaped profiles.
Preferably, the machining tool 11 is at least partially covered by a protective element or casing 16, as shown in Figs. 1-4.
The machine 100 comprises a handling unit 20 having the function of holding the material 200 suspended above the working plane 102, allowing the same to be repositioned.
Preferably, the handling unit 20 is of pneumatic type and comprises gripping means provided with one or more pneumatically-activated suction cups 21a, tiltable between an initial non-operative position, in which the suction cups 21a cannot interact with the material 200 irrespective of the position of the shaft 3, and a final operative position, in which the suction cups 21a can come in contact with the upper surface of the material 200 when the shaft 3 is lowered along the axis Z onto the same material 200.
Preferably, as shown in Figs. 1-4, the gripping means of the handling unit 20 comprises a plate 21 with corresponding suction cups 21a, and the plate 21 is integrally fixed to the tool-holder unit 10 and is rotatable along therewith about the axis E-E. With reference to the example of Fig. 4, the plate 21 is fixed by means of screws 21b to the protective element 16 of the circular blade 11. Alternatively, the plate 21 can be omitted and the suction cups of the gripping means of the handling unit 20 are directly formed in the protective element 16.
The first non-operative position of the plate 21 is vertical, as shown in Figs. 1, 2 and 4 and corresponds to a work position of the circular blade 11 facing the upper surface of the material 200; the second operative position of the plate 21 is horizontal and perpendicular to the shaft 3, as shown in Fig. 3 and corresponds to an non-operative position of the circular blade 11 lying parallel to the upper surface of the material 200.
Preferably, the rotation of the tool-holder unit 10 about the axis E-E and therefore of the gripping means of the handling unit 20, may vary between about 0° (i.e. with the plate 21 in a roughly vertical position) and about 90° (i.e. with the plate 21 in a roughly horizontal position).
Preferably, as in the case shown in Figs. 1-3, the rotating motor 14 is at least partially integrated with at least one of the rotation pins 15. Preferably, the motor 14 is a brushless motor. Moreover, the motor 14 preferably comprises a reduction gear (not shown in the figures).
The suction cups 21a are defined by the plate 21 and by one or more gaskets which delimit one or more areas on the surface of the plate 21 (i.e. the surface that can lie parallel to the upper surface of the material 200). The areas delimited by the gaskets have a closed perimeter, for example rectangular, circular or of a different shape.
With reference to Fig. 4, the plate 21 of the handling unit 20 preferably comprises three gaskets 22, 23a and 23b housed in suitable grooves formed in the material of the plate 21. The gaskets 22, 23a and 23b delimit corresponding substantially rectangular portions of the surface of the plate 21.
Preferably, the handling unit 20 also comprises one or more air suction ducts 26 connected to the suction cups 21a and in communication with the aforementioned portions. Moreover, surface grooves 25 are preferably formed on the surface of the plate 21, a plurality of openings 24 connected to the air suction ducts 26 being provided in the surface grooves 25.
When the plate 21 is in the operative position, and therefore horizontal, and is brought by the displacing apparatus 1 into abutment against the upper surface of the material 200, the suction of air through the ducts 26 generates a vacuum in the volumes defined by the same material 200, by the gaskets 22, 23a, 23b and by the plate 21. The vacuum degree is preferably adjusted to obtain an effective sucking effect which allows to lift the material 200 along the axis Z together with the tool-holder unit 10.
Preferably, the handling unit 20 also comprises one or more on-off valves 27 of the air flow along the suction ducts 26.
The suction is preferably generated by a pump (not shown) - or by a Venturi system - which is external to or forms part of the handling unit 20, to which the ducts 26 are connected.
The on-off valves 27 are preferably solenoid valves and each of them may be controlled independently from the others to cause the vacuum in just one of the suction cups 21a, for example in the suction cup 21a defined by the gasket 22, or in all of the suction cups 21a.
The solenoid valves are shown outside of the plate 21, but alternatively they can be arranged on the same plate 21 or in a seat associated thereto or on the protective element 16 of the tool-holder unit 10.
Preferably, the machine 100 also comprises a drive and control unit 103 (Fig. 1) equipped with an operator interface. The unit 103 is programmed to operate the displacing apparatus 1, the tool-holder unit 10 and the handling unit 20.
In the preferred embodiment illustrated in Fig. 4 it can be observed that the plate 21 has a through opening 29, free from suction cups 21a (in particular, the gasket 22 comprises a semi-circular shaped portion 22a close to the upper part of the through opening 29). The through opening 29 of the plate 21 allows a free access of the tool-holder unit 10 to a front free end 12a of the spindle 12.
Fig. 5 shows an enlarged view of such a front free end 12a, in which a nut 12b is visible, the hole 12c of which is arranged at the end of an axial hole of the spindle 12 which carries a fluid, for example water, intended to cool down the machine tools of the tool-holder unit 10. The aforementioned fluid comes from a respective supply line 6 described above.
A tool-holder coupling element 60, to which the tool-holder 50 can be removably coupled by means of a coupling assembly 61 that will be described hereafter, is housed in such a hole 12c. Both the tool-holder coupling element 60 and the tool-holder 50 are provided with respective axial holes 60c and 50c, which are in fluid communication with the hole 12c and carry the fluid intended to cool down the second machining tool of the tool-holder unit 10.
Preferably, the tool-holder 50 comprises a substantially cylindrical body 51 from which a coupling flange 54, which will be illustrated more in detail hereafter, is radially extending. In the body 51 a throat 53 is formed close to the coupling flange 54 so as to couple the tool-holder 50 in a substantially rack-type storage device (not shown) provided close to the machine 100.
Preferably, the tool-holder coupling element 60 comprises a cylindrical portion 62, which is fixed in such a hole 12c, i.e. the hole 12c forms a cylindrical seat for such a cylindrical portion 62.
Preferably, the cylindrical portion 62 is threaded and is screwed onto a corresponding inner thread of the hole 12c.
Preferably, the tool-holder coupling element 60 comprises a coupling flange 64 intended to cooperate with the coupling flange 54 of the tool-holder 50. In the preferred embodiment illustrated, the coupling flanges 54, 64 have an annular shape.
In the preferred embodiment illustrated in Fig. 6 it may be observed how the coupling flange 64 of the tool-holder coupling element 60 does not project from the outer surface of the plate 21, so that it does not hinder the operation of the gripping means of the handling unit 20, which can act when the tool-holder 50 is disassembled from the tool-holder coupling element 60 (i.e. also when the tool-holder coupling element 60 is disassembled from the hole 12c, as shown in Figs. 1-5).
According to a preferred embodiment, the coupling assembly 61 between tool-holder 50 and tool-holder coupling element 60 comprises:

a plurality of first magnets 65 with north polarity and a plurality of second magnets 66 with south polarity, provided in the coupling flange 64, and
a plurality of corresponding third magnets 55 with south polarity and a plurality of corresponding fourth magnets 56 with north polarity, provided in the coupling flange 54.

The coupling between the tool-holder coupling element 60 and the tool-holder 50 is accomplished when the first magnets 65 and the second magnets 66 are magnetically associated to the third magnets 55 and to the fourth magnets 56, respectively.
It should be observed that in another embodiment of the invention (not shown), the tool-holder coupling element 60, with the aforementioned characteristics and those which will be described hereafter, is integral with the spindle 12. In particular, the front free end 12a of the spindle 12 comprises the plurality of first magnets 65 and second magnets 66, possibly positioned in the coupling flange 64 integrally associated to the spindle 12.
Preferably, the magnets 55, 56, 65 and 66 are built in the coupling flanges 54 and 64, so that their outer coupling surface lies flush with the coupling flanges 54 and 64, respectively.
Preferably, the magnets 55, 56, 65 and 66 are equal in number (in the illustrated example there are four pairs of magnets 55, 65 and four pairs of magnets 56, 66).
In an alternative preferred embodiment, just two pairs of magnets 55, 65 and just two pairs of magnets 56, 66 may be provided. More preferably, however, a greater number of such pairs, for example three, four, five or six may be provided, so as to optimise - as outlined above - the coupling operations between the front free end 12a of the spindle 12 and the free end of the tool-holder 50.
Preferably, the magnets 55, 65 are circumferentially arranged alternating with the magnets 56, 66.
Preferably, the magnets 55, 56, 65 and 66 have coupling surfaces provided with a circular shape having the same size.
In a preferred embodiment, the coupling assembly 61 between the tool-holder 50 and the tool-holder coupling element 60 also comprises a frusto-conical guide 57 formed on the tool-holder 50, and a corresponding frusto-conical seat 67 formed in the tool-holder coupling element 60. Preferably, the annular coupling flange 54 of the tool-holder 50 coaxially extends around the frusto-conical guide 57; similarly, the annular coupling flange 64 of the tool-holder coupling element 60 coaxially extends around the frusto-conical seat 67.
In the preferred embodiment illustrated, the coupling assembly 61 comprises a mechanical coupling device 63 provided with elements cooperating in abutment relationship and capable of making the tool-holder 50 and the spindle 12 integrally rotatable with each other.
Preferably, the elements cooperating in abutment relationship of the mechanical coupling device 63 comprise a plurality of driving pegs 58, axially extending from the tool-holder 50, and a corresponding plurality of respective housing seats 68 of such driving pegs 58, formed in the tool-holder coupling element 60.
In an alternative preferred embodiment, a single pair of driving pegs 58 may be provided, preferably with more than two respective housing seats 68, so that the driving pegs 58 can couple to one of such housing seats 68, in a certain number of different angular positions.
In a further preferred embodiment of the invention (not shown), the driving pegs 58 are formed on the tool-holder coupling element 60, whereas the housing seats 68 are formed in the tool-holder 50.
In the preferred example illustrated in Figs. 7 and 8, four driving pegs 58 and eight respective housing seats 68, respectively arranged on the annular coupling flanges 54 and 64, are provided. In particular, the driving pegs 58 and the housing seats 68 are circumferentially arranged at an equal distance form each other on the annular coupling flanges 54 and 64, respectively.
Preferably, the driving pegs 58 are circumferentially interposed between the magnets 55 and 56, and the respective housing seats 68 are circumferentially interposed between the magnets 65 and 66.
In this way, any alignment between the magnets 55, 56 and 65, 66 involves a corresponding alignment between the driving pegs 58 and the respective housing seats 68.
Preferably, the driving pegs 58 have a shorter axial extension than that of the frusto-conical guide 57.
In the preferred embodiment shown in Fig. 8, the driving pegs 58 comprise a cylindrical portion 58a and a substantially conical end portion 58b, while the housing seats 68 have a cylindrical section to house the cylindrical portion 58a of the driving pegs 58.
In Fig. 9 it may be observed that the tool-holder 50 comprises, at a front end thereof 59a, a seat 59b - preferably conical - adapted to house the second machining tool 28 (shown in Fig. 8).
In a preferred embodiment, the tool-holder unit 10 further comprises a plug 70 adapted to close the frusto-conical seat 67 of the tool-holder coupling element 60 when the tool-holder 50 is disassembled from the tool-holder coupling element 60.
Preferably, the plug 70 is provided with a frusto-conical portion 77 extending from a disc-shaped portion 79 and which may be inserted with a substantial shape coupling in the frusto-conical seat 67.
Preferably, the plug 70 is made of a metallic material and is removably coupled to the tool-holder coupling element 60 by means of at least one magnet 69, arranged in a flat annular surface 64a arranged about the frusto-conical seat 67 (in the example illustrated in Figs. 7 and 10 two magnets 69 are provided, arranged on diametrically opposite sides with respect to the frusto-conical seat 67).
Preferably, the flat annular surface 64a of the coupling flange 64 is recessed with respect to the coupling flange 64, so that the disc-shaped portion 79 of the plug 70 mounted on the tool-holder coupling element 60 lies flush with the coupling flange 64, as shown in Fig. 12.
A preferred embodiment of the method for machining block or slab materials according to the invention which may be carried out by means of the machine 100 illustrated above, will now be described.
The method essentially comprises the step of positioning the block or slab material 200 to be machined on the working plane 102 and then the step of moving the tool-holder unit 10 above the working plane 102, for example parallel and perpendicular to the same, to carry out machining operations on the block or slab material 200. This displacement step is carried out by means of the displacing apparatus 1 of the tool-holder unit 10, described above.
The machining operations carried out on the block or slab material 200 comprise a cutting operation carried out by a circular blade 11 which is mounted, as first machining tool, on the spindle 12 of the tool-holder unit 10.
The method also comprises the step of removably coupling a second machining tool 28 (for example a slot mill, a grinder, a drill bit, etc.) to the front free end 12a of the spindle 12 of the tool-holder unit 10 by means of the coupling assembly 61.
With such a second machining tool 28 an additional machining operation is carried out on the block or slab material 200 (for example milling, grinding, drilling, etc., depending upon the kind of the second tool used).
Preferably, the coupling step of the tool-holder 50 to the front free end 12a of the spindle 12 is carried out in the following way:

by bringing the spindle 12 close to the tool-holder 50,
by orienting the driving pegs 58 with respect to the respective housing seats 68 by means of the magnetic interaction between the magnets 55, 56 associated to the free end of the tool-holder 50 and the magnets 65, 66 associated to the front free end 12a of the spindle 12, in this case by means of the tool-holder coupling element 60; and
magnetically associating the front free end 12a of the spindle 12 to the free end of the tool-holder 50.

Preferably, the magnetic interaction between the magnets 55, 56 associated to the free end of the tool-holder 50 and the magnets 65, 66 associated to the front free end 12a of the spindle 12, in this case associated to the tool-holder coupling element 60, induces a rotation of the tool-holder 50 with respect to the spindle 12 adapted to bring in a condition of substantial alignment both the magnets 65, 66 and 55, 56 of opposite polarity associated to the spindle 12 and to the tool-holder 50, and the driving pegs 58 with the respective housing seats 68.
In a preferred embodiment, the method of the invention further comprises the step of storing a plurality of second machine tools 28 and of tool-holders 50 associated thereto in a substantially rack-type storage device (not shown) provided with locking elements of the tool-holders 50.
In a preferred embodiment, such locking elements can consist of resilient fork-shaped elements, for example made of metallic material, in which the tool-holders 50 are laterally inserted at the throat 53 formed in the body 51 of each tool-holder 50 near to the coupling flange 54.
Preferably, the coupling step of the second machining tool 28 to the front free end 12a of the spindle 12 (in this case to the tool-holder coupling element 60) is carried out by picking up a second machining tool 28 from the aforementioned substantially rack-type storage device by means of the coupling assembly 61.
In a preferred embodiment, the method of the invention further comprises the step of decoupling the second machining tool 28 from the front free end 12a of the spindle 12 (in this case from the tool-holder coupling element 60) of the tool-holder unit 10 by inserting the tool-holder 50 coupled to the tool-holder coupling element 60 in the substantially rack-type storage device along a lateral insertion path, and by moving the spindle 12 away from the storage device along a direction substantially perpendicular to the lateral insertion path.
In this way, the tool-holder 50 is detached from the tool-holder coupling element 60 overcoming the magnetic attraction force exerted by the magnets 55, 56 and 65, 66 and the spindle 12, or rather the tool-holder coupling element 60 associated thereto, and is once again ready to be removably coupled to a different machining tool 28 by means of the coupling assembly 61 according to coupling modes analogous to those outlined above.
In a preferred embodiment, the method of the invention further comprises the step of modifying the position of the block or slab material 200 on the working plane 102, i.e. the step of repositioning the block or slab material 200. This step is carried out by means of the handling unit 20, and firstly requires that the tool-holder 50 be detached from the front free end 12a of the spindle 12 as illustrated above, i.e. that the front free end 12a of the spindle 12 is not coupled to any tool-holder 50.
When it becomes necessary to reposition the block or slab material 200, the control unit 103 activates the handling unit 20, which is initially in the configuration shown in Figs. 1-2. The circular blade 11, raised with respect to the block or slab material 200, faces the latter and the plate 21 is vertical and cannot come in contact with the material 200. The circular blade 11 occupies a certain position along the axis Z with respect to the fork-shaped body 13 of the displacing apparatus 1.
Preferably, the handling unit 20 is activated by rotating the gripping means, or the plate 21 and the corresponding suction cups 21a, in the operative position, horizontal and proximal with respect to the material 200, shown in Fig. 3. Preferably, once rotated, the plate 21 occupies the position formerly taken by the circular blade 11 along the axis Z with respect to the fork-shaped body 13 of the displacing apparatus 1.
Preferably, the control unit 103 controls the displacing apparatus 1 to bring the plate 21 into abutment against the material 200, at least partially compressing the gaskets 22, 23a, 23b.
Preferably, the same unit 103 controls the opening of the valves 27 to achieve the air suction and create the vacuum necessary to obtain an effective suction effect with respect to the weight of the material 200. In this configuration, the material 200 firmly adheres to the plate 21 due to the effect of the vacuum and is displaced by the displacing apparatus 1 into the new position foreseen based on the coordinates X, Y and Z and based on the rotation about the axis Z programmed in the control unit 103.
When the repositioning of the material 200 has been completed, the control unit controls the closing of the valves 27. Consequently, a recovery of pressure in the suction cups 21a of the plate 21 and a release of the material 200 are achieved; the plate 21 is now disengaged from the material 200 and the handling unit 20 may be moved away from the same and deactivated.
Preferably, the deactivation of the handling unit 20 comprises a rotation about the axis E-E to bring the plate 21 back into the initial position described above and at the same time to bring the circular blade 11 in a position ready for use.
Advantageously, the repositioning of the material 200 is obtained without affecting the data processing of the control unit 103, by simply exploiting the same reference system X, Y, Z and the corresponding algorithms.
In order to carry out a machining operation with the second machining tool 28, it is necessary to couple a second machining tool 28 to the front free end 12a of the spindle 12 of the tool-holder unit 10 as described above and to rotate the tool-holder unit 10 itself about the axis E-E, so that the second machining tool faces towards the material 200 (essentially, a rotation about the axis E-E analogous to that effected to bring the plate 21 of the gripping means in a horizontal position is carried out).
Advantageously, the tool-holder unit 10, the machine 100 and the method according to the present invention can also be used to machine the moulds used in the nautical field to make hulls, keels and structures made of fibreglass or similar materials.
Clearly, a man skilled in the art can bring numerous modifications and variants to the tool-holder unit of a machine for machining block or slab materials, as well as to the machine and to the method for machining block or slab materials described above, in order to satisfy specific and contingent requirements, all of which are in any case encompassed by the scope of protection of the present invention as defined by the following claims.

Claims

Tool-holder unit (10) of a machine (100) for machining block or slab materials (200), said tool-holder unit (10) being moveable above a working plane (102) of said machine (100) on which the block or slab material (200) to be machined is laid, wherein the tool-holder unit (10) comprises:
- a spindle (12) on which a circular blade (11) is mounted, and

- a coupling assembly (61) for removably coupling a second machining tool (28) to a front free end (12a) of the spindle (12), comprising a tool-holder (50) associated to the second machining tool (28) and at least one mechanical coupling device (63) provided with elements cooperating in abutment relationship (58, 68) to make the tool-holder (50) and the spindle (12) rotationally integral with each other,
characterised in that said coupling assembly (61) further comprises:
- at least two first magnets (65) with north polarity and at least two second magnets (66) with south polarity, associated to the front free end (12a) of the spindle (12) and circumferentially arranged alternating with each other at said front free end (12a),

- at least two third magnets (55) with south polarity and at least two fourth magnets (56) with north polarity, associated to a free end of said tool-holder (50) and circumferentially arranged alternating with each other at said free end of the tool-holder (50).
Tool-holder unit (10) according to claim 1, wherein said at least two first magnets (65) and said at least two second magnets (66) are associated to a tool-holder coupling element (60) associated to the front free end (12a) of the spindle (12).
Tool-holder unit (10) according to claim 2, wherein said at least two first magnets (65) and said at least two second magnets (66) are associated to a coupling flange (64) of the tool-holder coupling element (60) and said at least two third magnets (55) and said at least two fourth magnets (56) are associated to a respective coupling flange (54) of the tool-holder (50).
Tool-holder unit (10) according to claim 3, wherein the first magnets (65) are circumferentially arranged alternating with the second magnets (66) in the coupling flange (64) of the tool-holder coupling element (60), and the third magnets (55) are circumferentially arranged alternating with the fourth magnets (56) in the respective coupling flange (54) of the tool-holder (50).
Tool-holder unit (10) according to any one of the preceding claims, wherein the first (65) and the second (66) magnets associated to the front free end (12a) of the spindle (12) or, if present, to the tool-holder coupling element (60) associated to the front free end (12a) of the spindle (12) are arranged according to a single annular array or according to a plurality of concentric annular arrays.
Tool-holder unit (10) according to any one of the preceding claims, wherein the third (55) and the fourth (56) magnets associated to the free end of the tool-holder (50) are arranged according to a single annular array or according to a plurality of concentric annular arrays.
Tool-holder unit (10) according to any one of the preceding claims, wherein said coupling assembly (61) further comprises a frusto-conical guide (57), coaxially extending from said tool-holder (50), and a corresponding frusto-conical seat (67), formed in said front free end (12a) of the spindle (12) or, if present, in said tool-holder coupling element (60) associated to the front free end (12a) of the spindle (12).
Machine (100) for machining block or slab materials (200), comprising a working plane (102) on which the block or slab material (200) to be machined is laid and a tool-holder unit (10) according to any one of the preceding claims.
Machine (100) according to claim 8, further comprising a handling unit (20) coupled to said tool-holder unit (10) and provided with gripping means (21a) of the block or slab material (200) to be machined, wherein said gripping means (21a) are mobile between a first non-operative position, distal with respect to the working plane (102), and a second operative position, proximal with respect to the working plane (102), said gripping means (21a) being rotatable between said first non-operative position and said second operative position.
Method for machining block or slab materials (200) comprising the steps of:
a) arranging a block or slab material (200) on a working plane (102),

b) moving a tool-holder unit (10), comprising a spindle (12) on which a circular blade (11) is mounted, above the working plane (102),

c) carrying out a cutting operation on said block or slab material (200) by means of said circular blade (11),

d) rotating the tool-holder unit (10) about an axis substantially parallel to the working plane (102),

e) removably coupling a second machining tool (28) to a front free end (12a) of the spindle (12) of the tool-holder unit (10) by means of a coupling assembly (61) comprising a tool-holder (50) associated to the second machining tool (28),

f) carrying out an additional machining operation on said block or slab material (200) by means of said second machining tool (28),
wherein said coupling assembly (61) comprises at least one mechanical coupling device (63) provided with elements cooperating in abutment relationship (58, 68) to make the tool-holder (50) and the spindle (12) rotationally integral with each other;
characterised in that the coupling assembly (61) further comprises:
- at least two first magnets (65) with north polarity and at least two second magnets (66) with south polarity, associated to said front free end (12a) of the spindle (12) and circumferentially arranged alternating with each other at said front free end (12a),

- at least two third magnets (55) with south polarity and at least two fourth magnets (56) with north polarity, associated to a free end of said tool-holder (50) and circumferentially arranged alternating with each other at said free end of the tool-holder (50), and
in that said step e) is carried out by:
- bringing the spindle (12) close to the tool-holder (50),

- orienting the elements cooperating in abutment relationship (58, 68) of the mechanical coupling device (63) of the coupling assembly (61) by means of a magnetic interaction between the magnets (55, 56) associated to the free end of the tool-holder (50) and the magnets (65, 66) associated to the front free end (12a) of the spindle (12), and

- magnetically associating the front free end (12a) of the spindle (12) to the free end of the tool-holder (50).
Method according to claim 10, wherein said magnetic interaction between the magnets (55, 56) associated to the free end of the tool-holder (50) and the magnets (65, 66) associated to the front free end (12a) of the spindle (12) induces a rotation of the tool-holder (50) with respect to the spindle (12) adapted to bring in a substantially aligned arrangement both the magnets of opposite polarity associated to the spindle (12) and to the tool-holder (50), and the driving pegs (58) with the respective housing seats (68).
Method according to claim 10, wherein the elements cooperating in abutment relationship (58, 68) of the mechanical coupling device (63) of the coupling assembly (61) comprise:
a) a plurality of driving pegs (58) axially extending from one of said free end of the tool-holder (50) and said front free end (12a) of the spindle (12), and

b) a corresponding plurality of housing seats (68) of said driving pegs (58), formed in the other of said free end of the tool-holder (50) and said front free end (12a) of the spindle (12);
and wherein said step e) is carried out by orienting the driving pegs (58) with respect to the respective housing seats (68) by means of said magnetic interaction.
Method according to claim 10, further comprising the step of storing a plurality of second machining tools (28) and of tool-holders (50) associated thereto in a substantially rack-type storage device provided with locking elements of said tool-holders (50).
Method according to claim 13, wherein said coupling step e) is carried out by picking up a second machining tool (28) from said substantially rack-type storage device by means of said coupling assembly (61).
Method according to claim 13, further comprising the step of
g) decoupling the second machining tool (28) from said front free end (12a) of the spindle (12) of the tool-holder unit (10) by inserting the tool-holder (50) coupled to the tool-holder coupling element (60) in the substantially rack-type storage device along a lateral insertion path, and moving the spindle (12) away from said storage device along a direction substantially perpendicular to said lateral insertion path.