The present invention regards a system for calibrating and/or squaring squareable elements, such as ceramic or natural stone items and the like, and for example ceramic tiles, stone materials, glass, composite materials, etcetera; in addition, the relative processing method, obtained by means of the abovementioned calibration system, is also provided.

STATE OF THE ART

With particular reference to the field of the ceramics industry for manufacturing items such as plates, sheets or tiles, or to the field of natural stones, it is known to carry out processing, such as calibration and/or squaring of the edges, in a manner so as to make the aforesaid items have the required size and/or geometric tolerances.

For the execution of the size calibration and squaring, the prior art provides calibrating and/or squaring machines which provide for transferring the squareable element to be calibrated and/or squared along a path, during which the element itself is worked at two opposite edges thereof, parallel to the direction of advancement, by a plurality of mandrels with opposite front grinding wheels. Each grinding wheel is driven in rotation at a pre-established speed by a respective motor.

The grinding wheels are distributed in opposite pairs along the path and the distances between the two opposite grinding wheels of each pair are adjusted as a function of the size and/or geometry to be obtained and of the position occupied by the pair of grinding wheels along the path.

The driving of the squareable element is attained by means of conveyor belts, against which the element is abutted, and on which it is pressed by pressing members, for example rollers or belts, which are moved with movement that is synchronous with the lower conveyor belt against which the squareable element is abutted.

The known embodiments, which execute the calibration and the squaring of square sheets or tiles, have - after a first series of grinding wheels like that just described above - a rotation device which rotates the squareable element, generally by 90°, provided with means for introducing and transferring the rotated squareable element to a second calibration unit substantially identical to the first which executes the calibration of the two remaining opposite sides.

The distance between each of the pairs of opposite grinding wheels progressively decreases along the path completed by the squareable element for the working of each respective pair of opposite edges thereof.

Nevertheless, in the machines of known type, in order to obtain the suitable calibration and/or squaring of the squareable element, this must be worked by a high number of pairs of opposite front grinding wheels, e.g. seven or even fourteen pairs of grinding wheels for each calibration unit of a respective pair of opposite edges of the item.

Hence, each machine can require even seven to fourteen pairs of front grinding wheels overall.

The use of so many front grinding wheels clearly involves, for the machines of known type, economical, energy and size disadvantages.

From the economical standpoint, there are in fact the obvious extra-costs determined by such a high number of front grinding wheels. From the energy standpoint, it is quite clear that there is high consumption due to the power supply of the respective motors of the grinding wheels, with further negative economical effects. In addition, the machines of known type have excessive size, since they must have a considerable longitudinal extension in order to be able to house all the pairs of front grinding wheels required. There is therefore the need to improve the art of calibrating and/or squaring squareable elements, such as ceramic or natural stone items and the like, for example plates, sheets or tiles, stone materials, glass, composite materials etcetera.

EP0980740A2 teaches a solution according to the state of the art.

OBJECTS OF THE INVENTION

Therefore, the main object of the present invention is to improve the state of the art in the field of calibration and/or squaring systems for squareable elements, such as ceramic or natural stone items and the like. In the scope of such task, one object of the present invention is to provide a calibration and/or squaring system that comprises a limited number of elements for processing the edges of the squareable elements.

Another object of the present invention is to provide a calibration and/or squaring system which allows limiting the energy consumption with respect to the machines of known type.

A further object of the present invention is to provide a calibration and/or squaring system with limited size.

Another object of the present invention is to provide a system for calibrating and/or squaring squareable elements, such as ceramic or natural stone items and the like, which is easy to make and with competitive costs.

These and still other objects of the present invention are achieved by a calibration and/or squaring system according to claim 1.

The dependent claims refer to preferred and advantageous embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will be more evident from the detailed description of a non-exclusive embodiment of a calibration and/or squaring system for ceramic or natural stone items and the like, according to the present invention, given as a non-limiting example, in the enclosed drawing tables in which: figure 1A is a schematic perspective view of a calibration and/or squaring machine of known type;

figure IB is a schematic perspective view of a calibration and/or squaring system according to the present invention;

figure 2 is a detailed top view of a pair of elements for working the opposite edges of a squareable element, of a calibration and/or squaring system according to the present invention;

figure 2A is a side view that illustrates a roller of a system according to the present invention while it works an edge of a squareable element;

figure 3 is a detailed front view of the pair of processing elements pursuant to figure 2; figure 4 is a detailed front view of a pair of elements for working the opposite edges of a squareable element, with blowing and cooling means illustrated as well.

EMBODIMENTS OF THE INVENTION

With reference to the enclosed figures, a calibration and/or squaring system for squareable elements A is indicated overall with reference number 1.

The squareable elements A can be ceramic or natural stone items and the like, and for example ceramic tiles, stone materials, glass, composite materials, etcetera.

The calibration and/or squaring system comprises a support structure 2 for at least one conveyor belt 3, for the transport and advancement on a respective bearing plane 4a of the squareable elements A according to a predetermined direction of advancement 4. Pressing members are also present, e.g. rollers or belts, adapted to abut against the squareable elements A driven by the conveyor belt 3 : the pressing members have movement synchronous with the belt 3, and allow stably retaining the squareable elements A during the advancement and working thereof. The pressing members are not represented in the figures since they are not part of the present invention.

The squareable elements A are provided with at least one edge B to be worked arranged substantially parallel to the direction of advancement 4.

The system 1 comprises at least one processing unit 5 for the calibration and/or the squaring of the edge B.

In particular the aforesaid processing unit 5 comprises a substantially cylindrically shaped abrasive roller 6 provided with an axis 7 and with a lateral abrasive surface 6a. The abrasive roller 6 is rotatable around the axis 7, actuated by a respective motor 8; the motor 8 can generally be of electric type.

More in detail the lateral abrasive surface 6a of the roller 6 is positioned with the respective generatrices arranged substantially parallel to the edge B, or better yet to the main extension side B l (not to the thickness B2) of the edge B to be worked, and it is adapted to work in a substantially tangential manner against the edge B itself in accordance with one of the generatrices, in a manner so as to calibrate and/or square the element A.

In addition, the axis 7 is substantially parallel to the direction of advancement 4, in particular to the direction of advancement of the conveyor belt 3. Therefore, the axis 7 of the abrasive roller or rollers 6 is parallel to the direction of advancement of the squareable elements A on the belt 3.

More particularly, the axis 7 can be tilted with respect to the direction of advancement 4 by a first and/or second tilt angle, which will be better described hereinbelow, equal to or less than + or - 15°. Therefore, the expression "substantially parallel to the direction of advancement 4" is thus intended to also include a variant as described now.

If desired, the axis of the roller or of the rollers 6 lies in a plane parallel to the main extension axis, e.g. horizontal, of a squareable element or sheet A or it is tilted with respect to one such horizontal plane, if desired tilted by a second tilt angle β equal to or less than + or - 15°, for example equal to + or - 5° or + or - 10°. Such second tilt angle β is evaluated or measured in a plane, vertical during use, in which a line parallel to the direction of advancement 4 lies together with the axis of the roller 6 or a projection of the axis 7 (if the axis is also tilted by a first tilt angle) on such vertical plane (see figure 2A).

Such tilt is useful for working the edge of the squareable elements A and more particularly for rendering such edge flat.

For such purpose, it must be considered that if the axis of the rollers is perfectly parallel to the direction of advancement of the belt and lying in a plane corresponding or parallel to the main extension plane thereof, the zone of contact between each roller and the squareable elements A would be very limited, unless rollers are used with very large radius or unless the rollers are strongly pressed against the squareable elements A, with the risk of ruining them or slowing them in an undesired manner.

If instead the rollers are tilted with respect to the vertical as stated above, each portion of the rollers engages and works the squareable elements A at a respective zone, so as to ensure working the edge of the squareable elements A for the entire thickness thereof.

The system can also comprise means for moving one or more rollers 6 set to vary the second tilt angle β of the axis 7 of a respective roller 6 relative to a horizontal plane. The roller or the rollers 6 are set to work squareable elements or sheets A according to a substantially flat, nearly vertical surface, hence perpendicular to the surface of the sheet itself.

The roller 6 can be a diamond or resinoid roller, which has a diamond abrasive lateral surface.

The processing station 5 can comprise members 9 for regulating the longitudinal tilt of the abrasive roller 6 with respect to the edge B according to a first tilt angle a. By first tilt angle a it is intended the angle delimited by the axis 7 of the roller with respect to a plane, vertical during use, in which the direction of advancement 4 or a line parallel thereto lies. Such first tilt angle is evaluated or measured in a plane, horizontal during use, in which the direction of advancement 4 lies together with the axis of the roller 6, or a projection of the axis 7 (if the axis is tilted also by a second tilt angle) on such horizontal plane.

In addition, the processing station 5 comprises means 10 for adjusting the distance of the abrasive roller 6 from the edge B.

The system 1 can comprise at least one processing unit 5 for working at least one edge B, or a pair of opposed processing units 5, for the simultaneous working between two opposed rollers 6 of two respective opposite edges B of an element A having substantially quadrangular or rectangular shape with four sides B.

The opposed rollers 6 of a processing unit 5 are set to substantially work two respective opposite or parallel edges B of each squareable element A. The opposed rollers 6 of a processing unit 5 can be aligned along a direction transverse or orthogonal to the direction of advancement 4, i.e. each end of a roller 6 is substantially aligned with an end of the other roller 6. Clearly, the opposed rollers 6 of a processing unit 5 could also be slightly offset with respect to each other with reference to the direction of advancement 4.

In working the edge B of the element A, the roller 6 acts with the lateral abrasive surface 6a substantially over the entire length thereof, i.e. along the entire generatrix of the lateral surface.

Such characteristic, in working the edges B of the elements A, allows only one abrasive roller 6 to effectively replace, for example, four pairs of mandrels with front grinding wheels of known type, which - since they have an abrasive circular crown - have smaller work surface.

Indeed, the front grinding wheels have an abrasive circular crown not greater than 30- 40mm, beyond which the work speed of the front grinding wheels differs from the internal diameter to the external diameter of the abrasive circular crown and therefore cannot be optimized; hence, there must be a compromise between the work speed of the external diameter (greater diameter) and that of the internal diameter (smaller).

The abrasive roller 6 instead has the advantage of obtaining, as a function of the width thereof, a greater work surface with respect to the contact circular crown of the front grinding wheels.

The work surface of the abrasive roller 6 can be greater in a ratio of 1 to 3, up to 1 to 10, with respect to the front grinding wheels, and in addition, since the processing occurs in a tangential manner, the work speed is constant for the entire length of contact with the edge B and thus it can be regulated in an optimal manner.

Hence, numerous advantages are obtained: lower energy consumption due to the lower number of motors, lower size and cost of the squaring system. In addition, given the same energy consumption, it is possible to increase the work speed and the quantity of removed material.

Merely by way of a non-limiting example, the tilt angle a can have a width comprised between 1° and 15°, the abrasive roller 6 can have a diameter comprised between 180mm and 250mm, length between 100 mm and 300 mm, e.g. equal to about 200mm, and a rotation speed equal to about 6000 revolutions per minute.

In addition, each roller 6, in a direction concordant or coinciding with the direction of advancement 4, first has a first annular end 6c and then a second annular end 6d. In substance, the first annular end 6c is set to engage each squareable element A first, while the second annular end 6d is set to engage each squareable element last.

If desired, each roller 6 is arranged with first tilt angle a such that the first annular end 6c is at a distance from the middle line of the conveyor belt greater than the second annular end 6d.

In substance, two opposed rollers 6 together delimit a zone that is tapered in a direction concordant or coinciding with the direction of advancement 4, such that the zone present therebetween has greater width at the respective inlet end or first engagement end of each squareable element A and smaller width at the respective outlet end or final engagement end of each squareable element.

Such expedient takes under consideration the fact that the edge of the squareable elements 4 is progressively worked as it comes into contact with the rollers 6, limiting the width of the squareable elements 4.

The abovementioned members 9 for regulating the tilt of the abrasive roller 6 with respect to the edge B comprise at least one element 11 rotatable around a respective axis 12 orthogonal to the bearing plane 4a. Such rotatable element 11 supports at least the abrasive roller 6.

The aforesaid means 10 for adjusting the distance of at least the abrasive roller 6 from the edge B comprise at least one slide 13 for supporting the respective processing unit 5. Such slide 13 is movable according to a direction orthogonal to the direction of advancement 4.

More in detail, the aforesaid rotatable element 11 is supported on the slide 13, and the abrasive roller 6 and the motor 8 are associated with or connected to the rotatable element 11 itself. Members are also provided for positioning and removable locking 14 of the rotatable element 11 in a pre-established tilted configuration.

The rotatable element 11 is supported on the slide 13, for example with the interposition of at least one bearing 15.

Each of the rollers 6 comprises a respective rotation shaft 6b, and members are also provided for regulating the speed of the rollers 6 themselves.

Such speed regulation members comprise at least one mechanical revolution multiplier 16, which for example - as illustrated in figures 2, 3 and 4 - can be of the type with belt transmission 17 engaged with a first pulley 18 associated with the shaft of the motor 8 and with a second pulley 19 associated with the shaft 6b of the abrasive roller 6.

The motor 8 can be mounted with rotation shaft substantially parallel to the shaft 6b of the roller 6 to be moved and on the opposite side of the conveyor belt 3 with respect to the roller 6. With the above-described structure, when it is desired to vary the first tilt angle a or the second tilt angle β, it is possible to drive the rotation or displacement of the rotatable element 11, by moving the abrasive roller 6, the motor 8 and the mechanical revolution multiplier 16 or the belt 17 associated with or connected to the rotatable element 11 all together and by the same amount. Due to such expedient, it is not necessary to once again regulate the belt after the variation of the tilt angle of a roller 6.

Or, in another possible solution not shown in the figures, the members for regulating the speed can comprise an electric/electronic revolution multiplier, such as an inverter or the like associated with a respective motor 8. The inverter allows varying the power supply frequency for the motor 8, so as to allow the desired rotation speed thereof: by increasing the power supply frequency for the motor 8, the number of revolutions per minute thereof is consequently increased.

The assembly position of the abrasive roller 6 on its shaft 6b is invertible, such that when the cylindrical abrasive portion 6a is worn at one end of the abrasive roller 6, it is possible to rotate and use the other end, not yet used, in working on the edges B.

The system 1 can work under wet or dry conditions. The system 1 can comprise means for cooling and removing the removed material, e.g. water or another suitable liquid can be used, or air or another gas can be used.

In the embodiment illustrated in figure 4, the system 1 comprises blowing or cooling means 20 with air or gas jet, adapted to move the particles and the powders generated by working away from the zone of contact between the rollers 6 and the edges B, and also to cool the rollers 6 themselves.

Such blowing and cooling means 20 comprise at least one outlet mouth 21 situated in proximity to the contact zone between the rollers 6 and the edges B in order to convey the gas j et thereto.

The system 1 can also comprise members for sucking the particles and powders generated from the working of the edges B of the squareable elements A. The suction members are not represented in the figures.

The system 1 comprises in particular a first processing station 22 provided with at least one processing unit 5, or a pair of opposed processing units 5, for calibrating and/or squaring at least one edge B, or two opposite edges B of the elements A.

After the processing unit 5, several mandrels 25 of conventional type follow, for example three or four on only one side or with opposed pairs, with front cup grinding wheels for finishing and for conferring planarity to the edge or to the edges B.

The system 1 then comprises a group 23 for rotating and feeding the squareable elements A to a second processing station 24 provided with at least one processing unit 5, or a pair of opposed processing units 5, for calibrating and/or squaring at least one edge B, or two opposite edges B of the rotated elements A.

Also in this second processing station 24, several mandrels 25 follow with front cup grinding wheels for finishing and for conferring planarity to the edge or edges B.

In the embodiment represented in the figures, the axes 7 of the respective rollers 6 lie on a plane that is raised with respect to that of the bearing plane 4a, approximately placed at half the thickness of the elements A.

In order to adjust the height position of the rollers 6, means (not shown) can be provided for regulating the height of the plane of the axes 7 of the rollers 6 with respect to the bearing plane 4a.

Another object of the present invention is a method for calibrating and/or squaring squareable elements, such as ceramic or natural stone items and the like, which comprises the steps of: providing a system 1; positioning at least one squareable element A on at least one conveyor belt 3 so as to drive it according to a direction of advancement 4; working a pair of opposite edges B of the element A by means of the abrasive lateral surfaces 6a of the two opposed rollers 6 of a respective pair of opposed processing units 5 of a first processing station 22, the lateral abrasive surface 6a of each of the rollers 6 being positioned with its generatrices arranged substantially parallel to the edge B and being adapted to work in a substantially tangential manner against the edge B in accordance with one of the generatrices, the tilt of the rollers 6 with respect to the edges B being regulated by means of the regulating members 9, and the distance of said rollers 6 from the edges B being regulated by means of the adjusting members 10; rotating the at least one element A and feeding it by means of the rotation and feeding group 23 to at least one second processing station 24, working the other pair of opposite edges B of the squareable element A by means of the abrasive lateral surfaces 6a of at least two opposed rollers 6 of a respective pair of opposed processing units 5 of the second processing station 24, the lateral abrasive surface 6a of each of the rollers 6 being positioned with its generatrices arranged substantially parallel to the edge B, and being adapted to work in a substantially tangential manner against the edge B in accordance with one of the generatrices, the tilt of the rollers 6 with respect to the edges B being regulated by means of the regulating members 9, and the distance of the rollers 6 from the edges B being regulated by means of adjustment members 10; at the outlet of the system 1, picking up the worked squareable element A. The abovementioned rotation group 23 can carry out a rotation of 90° or even of a different angle as a function of the shape of the elements A.

The invention thus conceived is susceptible of numerous modifications and variations, all within the scope of the inventive concept.

In addition, all details can be substituted with other technically equivalent elements. In practice, the materials used, as well as the contingent shapes and sizes, can be of any type in accordance with requirements, without departing from the protective scope of the following claims.