Device for detecting the orientation of an edge of a slab-shaped element and machine comprising said detection device Technical field

This invention relates to the field of machining slab-shaped elements, for example slabs, tiles, made from ceramic material, stone, glass or the like.

More specifically, the invention relates to a device for detecting the orientation of an edge of a slab-shaped element and a machine for grinding slab-shaped elements comprising the above-mentioned detection device.

Background art

According to the prior art, the slab-shaped elements produced industrially, and which can be used as tiles for flooring and other types of covering require a grinding operation.

The main aim of this grinding operation is to guarantee the orientation and the dimensions of the sides of the slab-shaped elements in such a way as to allow the positioning alongside each other, during installation, without misalignment between the various slab-shaped elements.

In the field of the industrial production of slab-shaped elements this operation is carried out by means of grinding machines which are able to quickly process large quantities of products which feed in succession on a horizontal movement plane.

The sides of the products to be processed protrude laterally and come into contact with a succession of grinding wheels, which remove the excess material and move the outer perimeter flush and, if necessary, one or more inclined grinding wheels, for performance of the chamfering operation.

In commonly used machines, the grinding of the slab-shaped elements is performed in two steps.

In a first step, they are ground by specific grinding wheels facing each other facing the movement plane on two opposite sides of each slab.

The slabs are then rotated by 90° in such a way that the two remaining sides can be ground by further grinding wheels facing and alongside the movement plane. After the operation for rotation by 90°, there is a pusher device by which it is possible to orient the slab appropriately for the second grinding step.

More specifically, the pusher is used to orientthe two sides of the slab still to be ground in such a way that these are positioned in the correct way relative to the following two series of grinding wheels.

It is understood that correct adjustment of the pusher is necessary to obtain slabs which are perfectly square, that is to say, having all four corners at 90°.

In prior art machines, the adjustment of the pusher is performed manually based on the experience of the operator.

However, in order to facilitate this operation for adjusting the pusher, prior art machines are known, independent from the grinding machines, which, by using complex optical acquisition devices, are able to calculate the length of the diagonal of the slab in such a way as to obtain the values corresponding to a correct perpendicularity of the four corners of the slab.

Depending on the reading obtained by these machines, if the result is not satisfactory, the operator adjusts the pusher manually.

This type of machine for controlling the diagonal, although it is able to perform checks of the actual values of the diagonal of the slab, has major drawbacks.

One major drawback is due, for example, to the fact that these prior art machines, as they are independent of the grinding machine, have a very high cost and require a large space in the production environment in order to be installed.

A further drawback is due to the fact that the reading of the diagonal of the slab is performed completely independently of the actual direction of feeding and working of the slab on the grinding machine and this makes precise adjustment of the pusher difficult, in order to compensate for any shape irregularities.

Moreover, the machine for controlling the diagonal is usually located a few metres away from the grinding machine; for this reason, the correction of any machining errors is not immediate, resulting in significant production waste or in any case lower quality levels.

In this context, the technical purpose which forms the basis of this invention is to provide a device for detecting the orientation of slab-shaped elements and relative machine for grinding slab-shaped elements which overcomes at least some of the above-mentioned drawbacks of the prior art. Aim of the invention

The aim of the invention is to provide a device for detecting the orientation of an edge of a slab-shaped element and a relative machine for grinding slab-shaped elements which is able to optimise the command and control of a pusher device located upstream of the grinding machine.

Afurther aim isto provide a device for detecting the orientation of an edge of a slab-shaped element and a relative machine for grinding slab-shaped elements which is able to check the perfect perpendicularity of a slab-shaped element being machined in a fast and economical manner.

The technical purpose indicated and the aims specified are substantially achieved by a device for detecting the orientation of a sab-shaped element and a relative machine for grinding slab-shaped elements, comprising the technical features described in one or more of the accompanying claims.

The dependent claims correspond to possible embodiments of the invention.

Further features and advantages of the invention are more apparent in the non-limiting description which follows of a preferred embodiment of a device for detecting the orientation of slab-shaped elements and relative machine for grinding slab-shaped elements.

Brief description of the drawings

The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without restricting the scope of the invention and in which:

- Figure 1 is a top view of a machine for grinding slab-shaped elements according to the invention and

- Figure 2 is a schematic view of a detection device according to the invention.

Detailed description of preferred embodiments of the invention

A device 1 for detecting the orientation of an edge 10a, 10b of a slab-shaped element 10, according to the invention, is illustrated in the accompanying drawings and denoted in its entirety by the numeral 1.

This will be referred to below as "device 1". Another object of the invention is a machine 100 for grinding slab-shaped elements 10 which comprises at least one detection device 1 shown schematically, in its entirety, in Figure 1 and described below.

The slab-shaped element 10 must, at the end of production, generally have a quadrangular shape and therefore comprise two pairs of sides 10a (front), 10b (rear) and 10c, lOd (right and left sides) which are perfectly parallel to each other.

According to the invention, the device 1 for detecting the orientation of a front 10a or rear 10b edge of a slab-shaped element 10 advancing in a predetermined feed plane along a predetermined feed direction A with a predetermined direction shown with a relative arrow in the accompanying drawings, comprises at least two sensors 2a, 2b configured to intercept two respective points 12a, 12b of the front edge 10a of the slab-shaped element 10.

The front and rear characterisations of the edges 10a and 10b of the slab-shaped element 10 refers to the above-mentioned predetermined feed direction A shown in Figures 1 and 2.

By reading the two points 12a, 12b of the front edge 10a, the detection device 1 makes it possible to identify a straight line "R" passing through the two points 12a, 12b and then compare it with a predetermined reference straight line.

The predetermined reference straight line "R" may preferably correspond to a fixed straight line of a processing machine 100, such as, for example, the longitudinal directrix or the line perpendicular to the latter, shown in Figure 2.

Advantageously, the device 1 also comprises a structure 13 for supporting the at least two sensors 2a, 2b positioned in a fixed fashion relative to the predetermined feed plane.

If the device 1 is installed directly on a machine 100, the supporting structure 13 may comprise fixing means connected directly on a part of the main frame 101 of the machine 100 which is not movable during the machining operations.

It is important that the at least two sensors 2a, 2b are fixed at a predetermined fixed point of the machine 100, that is to say, in such a way as to keep a mutually fixed position during the operating operations of the machine 100 and make the detection independent of the movement of the machine tools 5

Advantageously, moreover, the support structure 13 is fixed on a device 102 for conveying the slab-shaped element 10 of the machine 100. The conveyor device 102 comprises two uprights, each of which comprises means for conveying the slab-shaped element 10, for example a pair of opposite belts, and a series of tools 5 for machining the slab-shaped element 10.

With reference to the drawings, the tools 5 machine the side edges 10c and lOd whilst the front 10a and rear 10b edges have already been machined by the first grinding step performed by a previous machine located upstream and not forming part of the invention. The reading of the sensors 2a, 2b is performed on the front edge 10a which has already been machined and, therefore, has already been made perfectly parallel to the edge 10b. Advantageously, the at least two sensors 2a, 2b are positioned above the predetermined feed plane of the slab-shaped element 10 and are configured to perform a reading of the above-mentioned respective at least two points 12a, 12b of the edge 10a which is vertical and perpendicular to the predetermined feed plane.

Alternatively, the reading may be performed, again vertically and perpendicularly, but with the sensors 2a, 2b located below the predetermined feed plane.

According to another embodiment, the at least two sensors 2a, 2b are configured to read the at least two points 12a, 12b of the edge 10a in an vertical direction oblique relative to the predetermined feed plane.

This solution may also be performed by an upper or lower position of the predetermined feed plane.

According to yet another embodiment, the at least two sensors 2a, 2b are positioned at the same level as the predetermined feed plane.

For example, the two sensors 2a, 2b are installed at the outfeed station 120 of the machine 100 and pointed in the direction of the slab-shaped element 10 moving forward, and therefore, towards the sensors 2a, 2b.

It is also possible that the at least two sensors 2a, 2b are pointed in the direction of the slab-shaped element 10 away from the sensors 2a, 2b.

The sensors 2a, 2b comprise, for example, photocells, optical sensors or laser sensors.

In order to increase the reading precision in the case, for example, of slab-shaped elements having large dimensions, the device 1 may comprise three or more equidistant sensors to perform measurements, also equidistant, on the front edge 10a of the slab-shaped element 10.

The invention also relates to a machine 100 for grinding slab-shaped elements 10 comprising at least one detection device 1 as described above.

Figure 1 shows a machine 100 for grinding slab-shaped elements 10 according to the invention.

The machine 100 comprises a main frame 101 on which is installed a conveyor 102, for example of the double superposed belt type, configured for moving a plurality of slab shaped elements 10 along a feed direction A from a first infeed station 110 to an outfeed station 120.

The machine 100 also comprises a plurality of electric motors 5 connected to respective tools 5, and fixed stably to the main frame 101.

The tools 5 face the conveyor 102 (that is, the slab-shaped elements 10) between the infeed station 110 and the outfeed station 120.

The tools 5 are configured to perform the grinding operation on the side edges 10c and lOd of the slab-shaped elements 10 positioned on the conveyor 102 and moving along the feed direction A.

The machine 100 also comprises a detection device 1 as described above.

Advantageously, the predetermined feed plane of the detection device 1 corresponds to a means 102 for conveying the slab-shaped element 10.

Advantageously, moreover, the two sensors 2a, 2b of the device 1 are positioned at the outfeed station 120 of the machine 100, that is to say, downstream of a last machine tool

5.

More specifically, in this solution it is possible to check the slab-shaped element 10 with the detection device 1 at the end of production process, that is to say, when all four edges 10a, 10b, 10c, lOd have been machined during the grinding operation.

According to a preferred embodiment of the invention, the machine 100 comprises a pusher 4 for positioning the slab-shaped element 10 positioned upstream of the infeed station 110.

Following the reading performed by the detection device 1 relating to the orientation of the front edge 10a of the slab-shaped element 10 it is possible to perform the adjustment of the pusher 4.

The command and control of the adjustment of the pusher 4 may be performed either manually by an operator or automatically by means of the detection device 1. In the latter case, the detection device 1 comprises a unit for processing detected data and a respective command and control unit connected to the pusher 4 in order to command and control it in real time relative to measurements of the two points 12a, 12b taken on the front edge 10a by the device 1. The invention achieves the preset aims, overcoming the drawbacks of the prior art and bringing important advantages.

A first important advantage consists in the fact that a detection device 1 according to the invention makes it possible to continuously command and control the correct parallelism of the edges 10a (front), 10b (rear) and 10c, lOd (side) without having to shut down the machine 100.

Another important advantage consists in the fact that through a detection device 1 according to the invention the presence of a machine for controlling the diagonal of the slab-shaped elements 10 is no longer necessary; a machine which, as mentioned above, is very expensive and complex. A further important advantage consists in the fact that by means of a detection device 1 according to the invention any machining error is detected at the final step of the machining, that is to say, just after the passage of the slab-shaped element from the last tool of the machine. In this way it is possible to immediately and automatically correct any error so as to reduce production rejects to a minimum.