The present invention relates to a cutting machine for slabs of stone or stonelike material and to an associated machining method.

In particular, the present invention relates to the technical sector for obtaining bevelled tiles by means of cutting from a larger slab.

In the present description, for the sake of easier reference, the term "slab" will be used to indicate an unprocessed element which is yet to be cut into tiles, the term "strip" will be used to indicate a strip of material which will then be cut into tiles, and the term "tile" will be used for a generally smaller element obtained by cutting the slab or strip. The term "tile" therefore also includes panels, etc. The object of said simplification is merely to make reading of the present description easier, without however having any limiting effect on the scope of protection offered by the present description and by the accompanying claims.

The machines which are used for cutting the slabs into tiles may be provided with one or more diamond discs.

Single-disc machines are very widespread and, among these, those which nowadays are most used generally comprise two lateral support structure, above which a beam resting with its ends on the lateral support structures slides. A sleeve-holder carriage having, mounted thereon, a vertically sliding spindle-holder sleeve travels along the beam. A spindle designed to be equipped with a cutting disc of the diamond type is mounted on the sleeve. The machines according to the prior art are moreover provided with a workbench on which the slab to be cut is placed.

In order to allow cutting in several directions, the workbench or the spindle are rotatable about a vertical axis so as to be able to modify the direction of the cutting disc with respect to the slab to be cut.

Machines of this type are described for example in international patent applications WO2011 /039700 and WO2011/145005 and in Italian patent IT 1402232.

With machines according to the prior art it is therefore possible to perform cuts on the slabs in a plurality of different patterns, for example a chequer-board pattern, or more complex patterns, if the machines is provided with means for moving the strips or the slabs being machined.

It is known that, when producing tiles from a slab, it is often required to carry out bevelling of the edges of the slab. In fact, tiles of stone or stone-like material obtained from the cutting of a slab into smaller elements have rough edges such that the edges of the tile must be chamfered. This smoothing operation is referred to as bevelling.

The most common bevelling machines, which are suitable for only square or rectangular tiles, are provided with a workbench equipped with means for feeding the slabs being machined. One or both the sides of the bench are provided with spindles equipped with a tool, which is normally disc-shaped, for carrying out the bevel on the edge of the tile. The axis of rotation of the tool of the spindle which is designed to perform the bevel is normally inclined with respect to the surface of the tile.

Examples of these types of machines may be found, for example, in the Italian patents IT 1259129 and IT 1293159.

The machines of the prior art, although widely used and popular, are not without drawbacks.

Firstly, in order to obtain a tile provided with a bevel from an intact slab it is required to used at least two machines: a first machine for performing cutting of the slab and a second machine for performing bevelling of the edges.

This type of machining is therefore very costly both owing to the costs for purchase of the two machines and because of the operating costs, etc.

Moreover, it is required to transfer the material from one machine to another with a consequent increase in the machining times and loss of precision due to repositioning of the slab on the bevelling machine.

The operation is further complicated, if the elements to be bevelled have dimensions or a shape which vary greatly from each other.

It has also been noticed that, when the bevel is performed after cutting the slab, if the latter is not performed with extreme precision (straight) or if the slab has thicknesses which differ, even slightly, with respect to the nominal thickness, a non- optimum bevel, with dimensional variations along the edge will be obtained.

The object of the invention is therefore to solve at least partially the drawbacks of the prior art.

A first task of the present invention is to reduce the times and costs necessary for obtaining strips or tiles with bevelled edges from a slab.

A second task of the present invention is to provide a technology where cutting of the slab and bevelling of the edges of the tile may be performed on a single simple and low-cost cutting machine.

Moreover, the aim is to provide a cutting machine and a method associated with this machine where it is possible to obtain a uniform bevel along the entire machined edge also on tiles having dimensions which are variable and also with corners which are not right-angled.

The object and the tasks are achieved with a machine according to Claim 1 and a method according to Claim 14.

Further advantageous characteristic features according to the present invention are contained in the dependent claims.

The advantages and characteristic features of the present invention will emerge more clearly from the detailed description below of a number of examples of embodiment provided by way of a non-limiting example, with reference to the attached drawings in which:

Fig. 1 shows a schematic side view of a machine according to the present invention, in a first working configuration;

Fig. 1-A shows an enlarged view of the tool during machining shown encircled in Figure 1;

Fig. 2 shows in schematic form an enlarged view of the spindle shown in

Figure 1;

Figs. 3-A, 3-B, 3-C, 3-D show a schematic view of a tool for the bevelling operation according to the present invention;

Fig. 4 shows a schematic front view of the machine according to Fig. 1;

Fig. 5 shows in schematic form an enlarged view of the spindle shown encircled in Figure 4;

Fig. 6 shows in schematic form a side view of the machine already shown in Figure 1, in a second working configuration;

Fig. 7 shows an enlarged view of Figure 6 showing the spindle in the second working configuration;

Fig. 8 shows in schematic form a front view of a machine according to the present invention in a possible working configuration;

Fig. 9 shows in schematic form an enlarged view of the spindle shown encircled in Figure 8;

Fig. 10 shows a plan view of a machine according to the present invention, during possible machining of a slab;

Fig. 10-A shows an enlarged view of a part of the slab shown in Figure 10; and Fig. 11 shows an alternative embodiment of a part of a machine according to the present invention.

In the accompanying figures the reference number 38 denotes a machine according to the present invention. With reference to the embodiment shown in Figure 4, the machine 38 according to the present invention comprises a frame formed by two lateral support structures 40, 42 and by a beam 44.

A workbench 46 is provided between the lateral support structures 40, 42. Advantageously, the workbench 46 may be provided with a conveyor belt 48. Irrespective as to whether the conveyor belt 48 is present or not, the workbench 46 is lined with a sacrificial material (typically wood or plastic) suitable for receiving incisions made by cutting means. This lining is known per se to the person skilled in the art and therefore will not be further described.

The support structures 40, 42 may be provided with inlet/outlet openings 50,

52 for the slabs to be machined or the slabs already machined.

In accordance with a first embodiment of the present invention, shown in the accompanying figures, the beam 44 rests with its ends 54, 56 on the lateral support structures 40, 42. Advantageously, movement means 58, 60 may be provided between ends 54, 56 of the beam and lateral support structures 40, 42. The movement means 58, 60 may be of the type known per se to the person skilled in the art, comprising, for example, rails, flat guides, etc. and a drive system (not shown in the attached figures) for moving the beam along the lateral support structures 40, 42.

According to a possible alternative embodiment of the present invention (not shown in the attached figures), the lateral support structures consist of two columns at the top of which the ends of the beam are fixed, thus forming a single body with a gantry structure. In this case, for displacement of the beam, the entire gantry structure is moved by means of a suitable drive system which may be easily imagined by the person skilled in the art.

A sleeve-holder carriage 62 is provided on the beam 44. The sleeve-holder carriage 62 is slidable along the beam 44. The means designed to move the sleeve- holder carriage are of the type known per se to the person skilled in the art and for this reason will not be further described.

A sleeve 64, slidable vertically with respect to the carriage 62, is mounted on the sleeve-holder carriage 62. In this case too, since the means for moving the sleeve 64 with respect to the carriage 62 are known per se to the person skilled in the art, they will not be described in further detail.

A spindle 66 is mounted at the end of the sleeve 64.

In accordance with a first embodiment of the present invention, the spindle 66 is mounted rotatably about a substantially vertical axis, i.e. substantially perpendicular to the workbench. According to an alternative embodiment, it is the workbench 46 which is rotatable about a substantially vertical axis.

The means for moving the spindle and/or the workbench are technical solutions which are known to the person skilled in the art and will therefore not be further described.

Owing to the possibility of directing in varying ways the spindle with respect to the slab, oblique cuts may be performed, as already explained further above.

The spindle 66 is provided with a spindle drive unit 68 which has an output shaft 67.

The spindle 66 is provided with a cutting disc 70, which is keyed onto the shaft 67 of the spindle 66. Advantageously the cutting disc 70 may be keyed onto the shaft 67 by means of suitably shaped clamping flanges 71, 73.

The cutting disc 70 has an axis substantially parallel to the plane of the workbench 46 so that the cutting disc 70 is oriented to perform the cut in a direction substantially perpendicular to the plane in which the workbench 46 lies.

The cutting disc 70 may be of the type known per se to the person skilled in the art and will therefore not be further described.

In the machine according to the present invention the spindle 66 is configured to engage operationally a bevelling tool 12.

The bevelling tool 12, shown in greater detail in Figures 2, 3-A, 3-B, 3-C, 3-D, comprises a bevelling disc 14 and flanges 32, 34 for clamping said disc. The locking in position of the clamping flanges 32, 34 may be performed by means of locking screws 36. Advantageously the bevelling disc 14 may have the form of a circular rim.

The disc 14 has a side face 16, 18 which in the vicinity of the outer edge 22 of the bevelling disc 14 is provided with a bevelling profile 20.

According to a first possible embodiment of the present invention, the bevelling disc 14 comprises a metal core on which a diamond bevelling profile 20 is welded, in the vicinity of the outer edge of the disc 14.

Figures 3-C and 3-D show a first embodiment of the bevelling profile 20 according to the present invention. The bevelling profile may comprise a tapered section 26 provided on at least one side face 16, 18 of the disc 14. Advantageously, in the case of a tapered section 26 on both side faces, the outer edge assumes a V-shaped form.

In this case the bevelling tool 12 is designed to perform an incision in the slab before the actual cut is performed with the cutting disc. Once the incision has been performed, the bevel is performed on the side of the tile which will be subsequently cut. In accordance with an alternative embodiment of the present invention, the bevelling profile 20 may comprise a tapered section 26 followed by a pre-cut section 28 which is generally straight and extends as far as the edge 22, lying substantially perpendicular to the axis 24 of the bevelling disc 14.

With this type of bevelling tool it is possible to perform also a pre-cut in the slab, as well as bevel, along the edge of the tile or the strip which will be subsequently formed.

The inclination and the length of the tapered section 26 and the length of the pre-cut section 28 may be different, depending on the geometrical form of the incision or the pre-cut which are to be performed on the slab and the bevel which is to be obtained on the edge of the tile.

Both in the embodiment which has a pre-cut section and in the embodiment which does not have it, the tapered section 26 may be curved. In this way the bevelling disc may be used to obtain a curved edge.

Advantageously, the bevelling tool 12 may be operationally engaged, on the outside of the cutting disc, as shown in Figure 2.

The expression "operationally engaged" is understood as meaning that means 72 for connecting together spindle 66 and bevelling tool 12 are provided. The connection means 72 comprise keying means which are designed to rigidly connect the bevelling disc 14 to the shaft 67 of the spindle 66 on which the cutting disc 70 is provided, so that the bevelling disc may be made to rotate by the said spindle.

In the engaged condition the bevelling disc is parallel to the cutting disc.

The connection means 72 may be of the type known per se, for example of the mechanical type, magnetic type or a combination thereof. Figure 2 shows the preferred embodiment of the present invention in which the connection means 72 comprise a connection of the permanent-magnet type. As is known, the connection of the permanent-magnet type is constructionally very simple and low-cost since it does not require any electrical or fluid circuitry.

In accordance with an alternative embodiment of the present invention, the connection means 72 may comprise screws, or joining systems of the mechanical type, such as interlocking joints which are known per se to the person skilled in the art.

Advantageously, as shown in the embodiment illustrated in Figure 2, the connection means 72 comprise the outermost flange 73 which grips the cutting disc and the innermost flange 32 of the bevelling tool. The flange 73 of the cutting disc may be provided with permanent magnets and a mechanical centring element for engagement with the innermost flange 32 of the bevelling tool 12. Advantageously, the diameter of the bevelling disc 14 is greater than the diameter of the cutting disc, as shown in the attached figures.

In this way it is possible to perform a pre-cut with the bevelling disc engaged also together with the cutting disc. After the incision or pre-cutting operation, the bevelling tool 12 may be disengaged from the spindle 66 and stowed away inside a storage station 76.

The mode of operation of the bevelling tool 12 according to the present invention is described below. The bevelling disc 14 is rotated about its axis 24 and is moved towards a slab to be machined, creating an incision or pre-cut, corresponding to the form of the its diamond profile.

If the bevelling profile, in addition to the tapered profile, also has a pre-cut section, a pre-cut is performed in the slab, while the tapered profile 26 forms the bevel at the point where the pre-cut has been formed.

In accordance with a possible embodiment the bevelling tool 12 is designed to cut the slab completely, namely through its entire thickness, cutting into the sacrificial support on which the slab rests, to a depth depending on the thickness of the slab; in this case, the cutting disc, although rotating, remains inoperative. Advantageously, for different slab thicknesses, tools with different-length machining bits could be used.

However, according to the preferred embodiment of the present invention, the bevelling tool is designed to perform a pre-cut, while cutting of the slab into tiles is obtained with a separate cutting disc of the type known per se to the person skilled in the art having a diameter smaller than that of the bevelling disc.

It is therefore clear that, compared to the prior art, there is a reversal of the steps performed to obtain tiles from a slab. In particular, before performing an incision or a pre-cut in the slab along one or more directions by means of a bevelling tool and, then, after removing the bevelling tool, complete cutting of the thickness of the slab is performed by means of the cutting disc fixed to the spindle.

In accordance with possible alternative embodiments of the present invention, the bevelling tool 12 may also be designed in other ways, while bearing in mind, however, the essential characteristic features mentioned further above.

In accordance with a possible embodiment of the present invention, the machine 38 has a tracking device 74 which is designed to sense the surface of the slab and convert this information into commands for positioning the bevelling disc 14. The tracking device may be provided on the spindle 66, as shown in the attached figures.

According to a first embodiment of the tracking device, it may comprise a shank 741 which is movable in the vertical direction and has at one end a feeler 742 such as a rotating body, for example a roller wheel, in a manner known per se to the person skilled in the art.

Advantageously, the tracking device 74 is designed to allow the bevelling disc to perform the incision or pre-cut in the slab, always to the same depth, independently of any irregularities in the flatness of the top surface of the slab, thus making it possible to obtain an edge of the slab with a regular and uniform bevel.

In fact, if the bevelling disc were to be kept at a constant height, when variations in thickness of the slab occur, the bevel would be formed in an irregular manner and, more precisely, where the thickness of the slab is greater, the bevel would be more pronounced, and where the thickness of the slab is smaller, the bevel would be less pronounced.

In order to overcome this problem the disc with bevel must penetrate into the material always over the same thickness.

Therefore with a variation in the thickness of the slab, said variation being due to any detected irregularities in flatness of the profile, the bevelling disc must correspondingly vary its heightwise position.

By means of a transducer, such as an encoder (not shown), the data detected, namely the heightwise position of the feeler, is converted into position information for a data processing system for example a computerized unit (not shown in the attached figures) which consequently controls the height of the bevelling disc 14, namely its distance from the top surface of the workbench, while keeping it always constant.

In other words, during the incision or pre-cutting operation, if the surface of the slab has irregularities, the feeler is raised or lowered and this movement is detected by the encoder which sends the data detected to the computerized unit of the machine so that the spindle is raised or lowered by the same amount.

Essentially, at each point along the path, the difference in height between the bottom end of the bevelling disc 14 and the bottom end of the feeler at the same point remains constant and equal to the depth of the incision or the pre-cut to be performed on the slab so that the bevelling tool penetrates into the material always to the same depth, forming a regular and uniform bevel.

It should be noted that the tracker and bevelling disc must be aligned so that the surface section sensed by the feeler is effectively the surface section which will be undergo the pre-cut.

Moreover, it must be considered that, since the tracker and bevelling disc for constructional reasons are spaced by a distance which is covered in a certain time, (this time depends on said distance and the feed speed of the bevelling disc), a time lag must be envisaged between detection by the tracker and operation of the cutting disc.

In accordance with alternative embodiments of the present invention, the tracking device 74 may be an optical device or an ultrasound device, which are designed to detect a distance. In particular, it may be a distance measurer of the laser type, known per se, as shown for example in Figure 11.

In Figure 11, in addition to the laser tracking device 74, a light beam generated by the laser device is also schematically shown by means of a continuous line 743, said light beam allowing precise detection of the distance between the device and the point which is struck by the beam.

In accordance with a possible embodiment of the present invention, a nozzle 744 may be provided for directing pressurized air towards the zone which is to be measured by means of the beam. One of the advantages achieved is that of obtaining a zone free from elements (cooling liquid or machining waste) which could affect the measurement.

Advantageously, a nozzle may also be provided in the proximity of the laser beam emitter in order to keep it free also from any machining liquids or waste.

The laser beam may be aimed at a point a few centimetres from the bevelling disc so that the time lapsing between reading of the distance of the slab and the passing movement of the disc is reduced, thus ensuring a greater reactivity of the system which must adjust this distance as already described above in the case of a mechanical tracker.

Advantageously, the laser beam is aimed at a point situated at a distance of between 10 and 40 cm from the edge of the bevelling disc during machining.

Detection of the distance takes place without any mechanical contact between the detector and the surface and therefore without exerting any pressure on the slab; the risk that the slab, which may not be flat, may flex owing to the action of said feeler, altering the reading, is thus avoided.

The device also has smaller dimensions than the mechanical tracking device, thus favouring the compactness of the application.

The cutting and bevelling method according to the present invention, carried out on a single machine substantially of the cutting type, will now be described in detail.

The method according to the present invention comprises:

a first step where a bevelling disc is engaged with a spindle comprising a cutting disc having a smaller diameter; and

a second step during which, by means of a bevelling tool of the type described above, at least one incision or a pre-cut is formed in a slab, wherein the incision or the pre-cut comprise the bevelling of at least one edge of the pre-cut;

a third step during which the bevelling disc is disengaged from the spindle; and a fourth step during which, if the bevelling tool is not present, cutting of the slab is performed by means of the cutting disc in the region of said at least one pre-cut performed during the previous step.

Advantageously, it is possible to perform all the pre-cuts using the bevelling disc and then perform all the respective cuts using the cutting disc. In accordance with an alternative solution, it is possible to perform pre-cuts or cuts in predetermined sequences.

In accordance with a possible embodiment handling devices 78 may be provided for repositioning the slabs during machining.

In accordance with a possible embodiment of the present invention, said movement devices 78 may be suction means which are provided on the disc cover of the spindle (as can be seen in Figures 4, 5, 8, 9). Advantageously, it is therefore possible, for example, to perform pre-cuts and longitudinal cuts which cover the entire slab, so as to obtain strips. Thereafter each strip may be arranged at a distance from the other strips and cut transversely in order to obtain the tiles with the desired chamfer.

Since said movement devices 78 are known per se to the person skilled in the art, they will not be further described.

The numerous advantages which can be achieved with the present invention are now evident.

Firstly a single-disc cutting machine with a spindle designed to engage optionally also with a bevelling disc as well as with the cutting disc is provided. In this way it is possible to perform both the operations using the same cutting machine, without having to remove the cutting disc, with an obvious advantage in terms of cost and time.

In this way it is no longer necessary to have a bevelling machine, with an obvious reduction in costs.

Moreover, it is also not required to have a sophisticated machine with a costly spindle fitted with automatic tool-changing device, the bevelling tool being instead simply connected to the spindle so as to cover the cutting disc, which is always present in the machine, without sophisticated attachment devices. Moreover the time required to carry out the operations is reduced significantly since it is not necessary to move the slab from one machine to another between the pre-cutting operation and the cutting operation.

Secondly, with the bevelling tool according to the present invention it is possible to provide regular and uniform bevels. In fact, the bevel does not depend on cutting of the slab since it is performed beforehand.

As a result of the tracking device it is possible to perform pre-cuts which are even more regular and uniform since any variations in thickness of the slab being machined may be taken into account.

The person skilled in the art, in order to satisfy specific requirements, may make modifications to the embodiments described above and/or replace the parts described with equivalent parts, without thereby departing from the scope of the accompanying claims.

In particular, it is possible to use a single disc both for the pre-cut and for the actual cut. In other words, it is conceivable to use a bevelling disc which is designed to cut the entire thickness of the slab as well as create a bevel at least on one edge of the cut; in this case the cutting disc, although rotating, remains inoperative.