AUXILIARY APPLICATOR DEVICE AND APPLICATION METHOD IN A DECORATION STATION FOR CERAMIC TILES OR SLABS

Abstract

 The auxiliary applicator device (1) is associated with a decoration station (2) for ceramic tiles or slabs (3), including an array of ordinary spray nozzles (5). A fan shaped jet (V) emitted by one of them, that does not conform to a standard (Vm) stored in electronic processing devices (11), is immediately detected by means of video cameras (10) associated with each one of these nozzles (5).
The ordinary spray nozzle (5), which fails, is then immediately stopped and its action is replaced by an additional nozzle (50), which was not operational until then.
The ordinary spray nozzle (5) so stopped is then replaced or cleaned, depending on the type of defect (V1, V2) found in the respective spray fan pattern (V).
In this way, the decoration station (2) does not have to be stopped and no ceramic tiles or slabs (3) to be rejected are produced.

Description

DESCRIPTION OF THE INVENTION

[0001] The present invention relates to the technical field of the ceramic industry, with particular reference to the decoration process of ceramic tiles and/or slabs to give their main surface the desired chromatic and/or graphic treatment.

PRIOR ART OF THE INVENTION

[0002] One of the most used of the above mentioned decoration processes is carried out by spraying a ceramic glaze on the tiles, which takes place in glazing chambers served by belt conveyors, which feed the tiles making them pass under the spraying nozzles inside.

[0003] In well-known chambers, also called multi-axis chambers, the ceramic tiles or slabs are moved at a constant forward speed by a conveyor, so as to enter, pass through an array of spray nozzles arranged along the same station in succession and finally exit.

[0004] Each nozzle, which usually sprays the same colour as the others, is carried by a carriage, operated by a translator moving in a direction crosswise to the forward direction, with back-and-forth movements: The glaze is then applied by combining the two movements, the tile advancement movement and the transversal movement of the nozzles.

[0005] For a uniform result it is necessary that the tiles advance under the nozzles with constant speed and without stops, to avoid the formation of areas with the glaze layer of different thickness.

[0006] The spray nozzles for this application are equipped with a head having a calibrated hole, which delivers the spray enamel with a fan-shaped jet.

[0007] The nozzle head is usually made of tungsten carbide, to give better properties of resistance to abrasion action exerted by the glaze ceramic, which, as known, incorporates suspended glass particles that can quickly erode even the hardest materials.

[0008] In fact, despite the use of this head, a nozzle of this type has an average operating time of about six hours, after which it must be replaced.

[0009] The abrasive action of the enamel on the calibrated hole of the nozzle progressively increases the angle of the fan pattern and therefore the size of the jet; when these become too large, the fan pattern of the enamel no longer falls within the parameters established for a correct application of the enamel, so that the nozzle must be replaced.

[0010] Obviously, the estimated operating time of six hours may not be real if changes of some kind occur, for example if the granulometry of the enamel is greater than usual.

[0011] In addition to the inconvenience mentioned above, which could be defined as "physiological", some impurities present in the enamel, such as a glass particle just larger than the established size, can in an unpredictable way be prevented from exiting the calibrated nozzle and remains blocked in that position; in this case, the spray pattern is no longer regular and homogeneous but is "split" as it is called in the jargon.

[0012] It is easy to understand, therefore, that even with a scrupulous planning of replacement interventions, having waste products, even in large numbers, cannot be prevented with absolute certainty.

[0013] If the financial loss can be considered limited for small tiles, it becomes very high in the case of large ceramic slabs, of the order of a few square meters of surface area, which are currently enjoying much success in high-end ceramic production.

[0014] As it is easy to understand, the dimensions of these slabs, in particular of the one in the advancement direction, greatly increase the probability of production waste in case of failure of even only one nozzle.

[0015] It should also be borne in mind that removing a large defective sheet from the line is a fairly laborious operation, which requires equipment and specialized personnel, with a downtime that is by no means negligible; all this increases the already considerable economic losses caused by the defective sheet(s) as such.

OBJECTS OF THE INVENTION

[0016] Object of the present invention is therefore to propose an auxiliary applicator device for a ceramic tile or slab decoration station, that can immediately detect if a nozzle produces a fan pattern that does not conform to the standard, and in this case deactivate it in a timely manner replacing its action with that of an additional nozzle, specially placed in the station and kept inoperative until then.

[0017] Another object of the invention is to maintain the functionality of the decoration station unchanged, without producing tiles or slabs with defective glazing, thanks to an additional nozzle, for a period of time sufficient to allow a maintenance intervention on the stopped nozzle so as to restore its correct operation.

[0018] Another object of the invention is to provide constructive solutions that allow carrying out the above maintenance operations without risk of damaging the glazing of ceramic tiles or slabs in the meantime passing through the decoration station.

[0019] Yet a further object of the invention is to propose a device that can be made in different versions, different for the number of additional nozzles being provided, in order to be best adapted to the characteristics of the decoration station to which it is associated.

[0020] Yet another object of the invention concerns the implementation of a method for an auxiliary applicator, in a decoration station for ceramic tiles or slabs, including operational steps designed to avoid production rejects, immediately detecting if a nozzle produces a fan pattern that does not conform to the standard, and in this case deactivate it in a timely manner replacing its action with that of an additional nozzle, specially placed in the station and kept inoperative until then.

SUMMARY OF THE INVENTION

[0021] These and other objects are wholly obtained by an auxiliary applicator device in a decoration station for ceramic tiles or slabs, said station, said station being intended for the application of ceramic enamel on these latter, which are moved at a constant feed rate by a conveyor, so as to enter said station, pass in succession by at least one spray nozzle arranged in the same station, and finally exit, with said at least one spray nozzle carried by a carriage, operated by a mover in a direction transverse to the forward direction, with back and forth movements, the said device including:

• at least one additional spray nozzle, fastened to a respective carriage that can be moved by a mover with a reciprocating movement parallel to the motion of said at least one ordinary spray nozzle, with said at least one additional spray nozzle maintained inoperative under conditions of regular operation of the aforesaid at least one ordinary spray nozzle;
• a plurality of video cameras, at least one of them being provided for each of said ordinary spray nozzles and designed to take, in real time, images concerning the spray pattern generated by the relative ordinary spray nozzle in each of the back and forth operating cycles performed by the latter;
• electronic processing means, designed to acquire images taken during each cycle by each of said video cameras and to compare them with a stored sample image, representing a spray pattern according to prefixed suitable specifications for a correct operation;
• a control unit, interfaced with said electronic processing means and intended for deactivation and selective stop of one or more of the aforementioned ordinary spray nozzles whose pattern has been found non-compliant, with the same control unit also provided for selectively activating, in suitable phase relation, said at least one additional spray nozzle to replace the function of the ordinary one being stopped, for a period of time at least sufficient to allow service operation on the latter.

[0022] The same objects are also achieved by means of an operative method fora n auxiliary applicator device in a decoration station for ceramic tiles or slabs, with said station being of the type designed for the application of ceramic enamel on these latter, which are moved at a constant feed rate by a conveyor, so as to enter said station, pass in succession by at least one spray nozzle arranged in the same station, and finally exit, with said at least one spray nozzle carried by a carriage, operated by a mover in a direction transverse to the forward direction, with back and forth movements, said method including:

• checking, during each said back and forth operating cycle, the spraying pattern generated by said at least one ordinary spray nozzle by comparing an image of said pattern and a stored sample image;
• enabling continuation of operation of said at least one ordinary spray nozzle when compliance of the generated spray pattern with respect to the sample image is ascertained;
• stopping operation of said at least one ordinary spray nozzle when non-compliance of the generated spray pattern with respect to the sample image is detected;
• activating, in suitable step relation, an additional spray nozzle to replace the function of the ordinary one being stopped, for a period of time at least sufficient to allow service operation on the latter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The characteristics of the invention under discussion will be evident from the following description of a preferred embodiment of the auxiliary applicator device, which is particularly suitable for implementing the operational steps of the method that is described in combination, in accordance with what is proposed in the claims and with the help of the enclosed figures, in which:

• Fig. 1 shows a schematic plan view of a decoration station for ceramic tiles and slabs, with the associated applicator device involved by the invention, under normal operating conditions;
• Fig. 2 shows, in a view similar to Fig. 1, a situation in which the applicator device is activated to replace a defective nozzle that is instead stopped;

• Fig. 3 shows, in an enlarged schematic side view, a correct spray pattern generated by a spray nozzle that is not worn out, in the station shown in Fig. 1;
• Fig. 4 shows, in a view similar to Fig. 3, a spraying fan pattern outside the correct parameters, generated by a worn out nozzle to be replaced;
• Fig. 5 shows, in a view similar to the previous figures, a spray pattern altered by a partial occlusion of the nozzle, which must be cleaned.

DETAILED DESCRIPTION OF THE INVENTION

[0024] In the above mentioned figures, reference 1 indicates the applicator device subject of the invention, as a whole.
the applicator device is associated with a decoration station 2 for ceramic tiles or slabs 3, of essentially know type, intended for the application of ceramic enamel on these latter.

[0025] The ceramic tiles or slabs 3 are moved at a constant forward speed by a conveyor 4, so as to enter, pass by spray nozzles 5, that are arranged along the same station 2, in succession and finally exit.

[0026] The figures show a decoration station 2 including preferably an array of spray nozzles 5 arranged in a series, with each of them carried by a carriage 6, which is driven by back and forth movements by a mover (not shown in detail) along a guide 7 extended transversally to the conveyor 4.

[0027] Usually, even if not necessarily, all the spray nozzles 5 of the decoration station 2 deliver glaze of the same colour; obviously it is possible that this decoration station 2 is followed by another station that adds different colours or transparent glazes to the same tiles or ceramic slabs 3, to complete a pre-selected decoration.

[0028] The applicator device 1 includes at least one additional spray nozzle 50, associated with a respective carriage 6, which can be operated by a mover along a corresponding guide 7 with back and forth movements parallel to the movements impressed on the ordinary spray nozzles 5.

[0029] The additional spray nozzle 50 is kept inoperative under normal operation of all ordinary spray nozzles 5, as better described below (Fig. 1).

[0030] In a preferred embodiment of the device 1, the additional spray nozzle 50 is advantageously positioned downstream of the above-mentioned array of ordinary spray nozzles 5, in accordance with the advancement direction of the ceramic tiles or slabs 3.

[0031] Obviously, two or more additional spray nozzles 50 can be provided as a variant, depending also on the number of ordinary spray nozzles 5 that make up this array.

[0032] A video camera 10 is associated to each of the ordinary spray nozzles 5 in order to take, in real time, images concerning the spray pattern V generated by the spray nozzle 5 in each of the back and forth operating cycles performed by the latter.

[0033] In the preferred embodiment shown in the figures, the additional spray nozzle 50 also has a video camera 10S associated with it that verifies the spray pattern V; if two or more additional spray nozzles 50 are provided, each of them will be equipped with a corresponding video camera 10S.

[0034] The images taken at each cycle by the video cameras 10, 10S, duly so coded as to know which ordinary spray nozzle 5, or additional spray nozzle 50, they belong to, are taken by electronic processing means 11 to be continuously compared, through a suitable software, with a stored sample image representing a spray fan pattern Vm conforming to prefixed specifications, suitable for a correct operation.

[0035] As long as the spray fan patterns V generated by the ordinary spray nozzles 5 are all evaluated after comparison as conforming to the pattern image Vm (Fig. 3), the operation of the decoration station 2 proceeds without any corrective action, with the additional spray nozzle 50 inactive, as already mentioned (Fig. 1).

[0036] As soon as the above comparison shows that a fan pattern V of a preestablished ordinary spray nozzle 5 includes a dissimilarity V1, V2 with respect to the normal pattern, a control unit 12, interfaced with said electronic processing devices 11, intervenes and selectively deactivates and stops the ordinary spray nozzle 5 in failure and, simultaneously, enables said at least one additional spray nozzle 50, so as to replace the function of the ordinary spray nozzle 5 that is instead stopped (Fig. 2).

[0037] The above-mentioned ordinary spray nozzle 5, deactivated for maintenance, is advantageously stopped in such a position as to be outside the transversal encumbrance of the aforesaid ceramic tiles or slabs 3 in transit within the aforesaid station 2, for a period of time at least sufficient to allow the necessary maintenance (see again Fig. 2).

[0038] In this way, ceramic tiles or slabs 3 can continue to pass through and be regularly glazed, without any risk of damage.

[0039] The electronic processing means 11 are equipped with suitable software programs designed to determine the cause of the non-conformity during the above-mentioned comparison between a scanned image of a spray pattern V and the stored pattern Vm.

[0040] There are essentially two types of anomalies recognised:

V1 - thisi is the wear of the tungsten carbide head of the nozzle 5, which in standard conditions has an operating life of about six hours and which results in a progressive increase in the angle of the fan pattern V and therefore in the size of the jet (Fig. 4);

V2 - this is the so-called "split" of the fan pattern (Fig. 5), which can occur unpredictably, due to some impurities present in the enamel, such as, for example, a glass particle just larger than the established size, which cannot escape from the calibrated hole of the nozzle 5 and locks in the middle of it. (V2)

[0041] When the anomaly found in the comparison between the fan patterns V, Vm is due to wear (V1), the maintenance intervention is obviously the replacement of the spray nozzle 5.

[0042] Device 1, in a possible constructive solution, includes means (not shown in detail as of intuitive comprehension) associated to each of said ordinary nozzles 5 as well as to said at least one additional spray nozzle 50, provided for the 180° overturning of each of them, to be carried out during the above mentioned maintenance when there is a "split" fan pattern V2.

[0043] After the first overturning, compressed air is ejected from the enamel supply channel, which removes and expels any impurities located in the outlet of the same nozzle 5 that is stopped; this is followed by a further 180° overturning to bring the nozzle back to the correct working position.

[0044] As a further construction variant, it is possible to provide suitable actuators (also not shown) to carry out the above mentioned overturning.

[0045] The occurrence of a non-compliance fan pattern V1, V2 can affect more than one of the above mentioned ordinary spray nozzles 5, even simultaneously, or almost simultaneously, in which case the control unit 12 intervenes to activate more than one additional spray nozzle 50, if they are present.

[0046] If this is not the case, i.e. if it is necessary to deactivate and stop a higher number of ordinary nozzles 5 than the number of additional nozzles 50 available or that can be activated to replace them, the control unit 12 is suitable for slowing down the aforementioned conveyor 4 of ceramic tiles or slabs 3 by a pre-selected value, so as to keep the thickness of the ceramic glaze applied to the latter constant, even if the number of nozzles active is lower.

[0047] The operation of the applicator device 1 reflects the operating steps of a method in which it is used:

• checking, during each said back and forth operating cycle, the spraying fan pattern V generated by said at least one ordinary spray nozzle 5 by comparing an image of said fan pattern V and a stored pattern image Vm;
• enabling continuation of operation of said at least one ordinary spray nozzle 5 when compliance of the generated spray fan pattern V with respect to the sample image Vm is ascertained;
• stopping operation of said at least one ordinary spray nozzle 5 when non-compliance V1, V2 of the generated spray fan pattern with respect to the sample image is detected;
• activating, in suitable step relation, at least one additional spray nozzle 50 to replace the function of the ordinary one 5 being stopped, for a period of time at least sufficient to allow service operation on the latter.

[0048] The method also provides, during the activation of said at least one additional spray nozzle 50, the check of the spraying fan pattern V generated by the same, at each bacn and forth operating cycle by comparison between an image taken of said fan pattern V and the aforementioned stored sample image Vm.

[0049] The method also provides that the above mentioned stop for maintenance of said at least one ordinary spray nozzle 5 takes place in such a position as to be outside the transversal encumbrance of said tiles or ceramic slabs 3, moving within said station 2.

[0050] According to an optional step of the method, when the above mentioned maintenance of the ordinary spray nozzle 5, or of an additional spray nozzle 50, concerns the presence of localized impurities in the respective outlet, an initial 180° overturning of the nozzle 5, 50 is carried out, followed by an ejection of compressed air from the enamel supply channel, to remove and expel said impurities; subsequently the nozzle 5, 50 is again overturned 180° to bring it back to the correct working position.

[0051] The method can advantageously provide for a slowing down of said conveyor 4 of the aforesaid ceramic tiles or slabs 3, upon occurrence of a deactivation and stoppage that involves a number of ordinary nozzles 5 greater than that of the aforesaid additional nozzles 50 that can be activated to replace them, in order to maintain constant the thickness of the ceramic glaze applied on the same ceramic tiles or slabs 3.

[0052] From the above description, concerning both the applicator device 1 and its operation, and the operating method implemented, the main characteristic of the invention in question is very clear. The invention allows immediate detection of whether a nozzle produces a fan pattern that does not comply with the standard, and in this case it promptly deactivates it, replacing its action with that of an additional nozzle, prepared for this purpose in the decoration station and kept out of operation until then.

[0053] With this important advantage, given by the additional nozzle, the decoration station is kept in operation without changes in the glazing process, so that defective tiles or slabs are avoided, for all the time necessary to intervene on the stopped nozzle, to replace it or restore its proper operation.

[0054] The fact that the nozzle to be maintained has been stopped outside the overall encumbrance of the ceramic tiles or slabs, which are in the meantime moving, makes these maintenance operations convenient and risk-free for the tiles or slabs themselves.

[0055] The applicator device, as specified, is versatile and can be adapted to different conditions of use, in particular by providing one or more additional nozzles.

[0056] All the advantageous aspects can be found in the method proposed in combination with the aforementioned auxiliary applicator device, whose operating steps make it possible to avoid production waste in a station for decorating ceramic tiles or slabs, with the cost savings that this entails.

[0057] It is understood, however, that what is described above is illustrative and not limiting, therefore any variations in detail that may be necessary for technical and/or functional reasons, both in the method and in the system, are considered from now on within the protective scope defined by the claims below.

Claims

1. Auxiliary applicator device in a decoration station for ceramic tiles or slabs, said station (2) being intended for the application of ceramic enamel on these latter, which are moved by a conveyor (4) so as to enter said station, pass in succession by at least one spray nozzle (5) arranged in the same station (2) and finally exit said station, said at least one spray nozzle (5) being carried by a corresponding carriage (6), operated by a mover in a direction crosswise to the forward one, with back-and-forth movements, said auxiliary applicator device (1) being characterised by including:

- at least one additional spray nozzle (50), fastened to a respective carriage (6) that can be moved by a mover with a reciprocating movement parallel to the motion of said at least one ordinary spray nozzle (5), with said at least one additional spray nozzle (50) maintained inoperative under conditions of regular operation of the aforesaid at least one ordinary spray nozzle (5);

- a plurality of video cameras (10), at least one of them being provided for each of said ordinary spray nozzles (5) and designed to take, in real time, images concerning the spray pattern (V) generated by the relative ordinary spray nozzle (5) in each of the back and forth operating cycles performed by the latter;

- electronic processing means (11), designed to acquire images taken during each cycle by each of said video cameras (10) and to compare them with a stored sample image (Vm), representing a spray pattern according to prefixed suitable specifications for a correct operation;

- a control unit (12), interfaced with said electronic processing means (11) and intended for deactivation and selective stop of one or more of the aforementioned ordinary spray nozzles (5) whose pattern (V) has been found non-compliant, with the same control unit (12) also provided for selectively activating, in suitable phase relation, said at least one additional spray nozzle (50) to replace the function of the ordinary one (5) being stopped, for a period of time at least sufficient to allow service operation on the latter.

2. A device according to claim 1, characterized by at least one video camera (10S) associated to said at least one additional spray nozzle (50), aimed at checking the spray pattern (V) generated by the latter.

3. A device in accordance with claim 1 or 2, characterized in that said electronic processing means (11) are provided with suitable software programs aimed at identifying, during the above mentioned comparison between an acquired image of a spraying pattern (V) and the stored sample image (Vm), the cause of non-compliance.

4. A device in accordance with claim 1 or 3, characterized by means associated with each of said ordinary spray nozzles (5) as well as with said at least one additional spray nozzle (50), provided for overturning each of them during said servicing operation, in order to expel any impurities located in the outlet mouth of the same stopped nozzle (5, 50).

5. A device according to any one of the previous claims, characterized in that said at least one additional spray nozzle (50) is positioned downstream of the aforementioned at least one ordinary spray nozzle (5), according to the forward direction of said ceramic tiles or slabs (3).

6. A device according to any one of the previous claims, characterized in that said at least one ordinary spray nozzle (5), when deactivated due to servicing operation, is stopped by said control unit (12) in such a position as to be clear of the encumbrance transverse space of said ceramic tiles or slabs (3) moving within said station (2).

7. Operating method for an auxiliary applicator device (1) in a decoration station (2) for ceramic tiles or slabs (3), said station (2) being intended for the application of ceramic enamel on these latter, which are moved by a conveyor (4) so as to enter said station, pass in succession by at least one spray nozzle (5) arranged in the same station (2) and finally exit said station, said at least one spray nozzle (5) being carried by a carriage (6), operated by a mover in a direction crosswise to the forward one, according to successive back and forth operating cycles, said method being characterized by:

- checking, during each said back and forth operating cycle, the spraying fan pattern (V) generated by said at least one ordinary spray nozzle (5) by comparing an image of said fan pattern (V) and a stored sample image (Vm);

- enabling continuation of operation of said at least one ordinary spray nozzle (5) when compliance of the generated spray fan pattern (V) with respect to the sample image (Vm) is ascertained;

- stopping operation of said at least one ordinary spray nozzle (5) when non-compliance (V1, V2) of the generated spray fan pattern (V) with respect to the sample image (Vm) is detected;

- activating, in suitable step relation, an additional spray nozzle (50) to replace the function of the ordinary one (5) being stopped, for a period of time at least sufficient to allow service operation on the latter.

8. An operating method according to claim 7, characterized by providing, during operation of said at least one additional spray nozzle (50), checking the spray fan pattern (V) generated by the latter, during each said back and forth operating cycle, by comparing an acquired image of said fan pattern (V) and said stored sample image (Vm).

9. An operating method according to claim 7, characterized by stopping operation of said at least one ordinary spray nozzle (5) in such a position as to be clear of the encumbrance transverse space of said ceramic tiles or slabs (3) moving within said station (2).

10. An operating method according to claim 7, characterized by a first overturning, during said servicing operation, of said ordinary (5) or supplementary (50) spray nozzle being stopped, where removal of any impurities within the respective outlet mouth is necessary, and a second overturning to bring said nozzle (5, 50) back into the correct operation position.

11. An operating method according to claim 7, characterized by slowing down said conveyor (4) carrying said ceramic tiles or slabs (3) when a deactivation and stoppage occurs for a number of ordinary spray nozzles (5) higher than that of said additional nozzles (50) which can be activated to replace them, so as to keep constant the thickness of the ceramic glaze applied on the same ceramic tiles or slabs (3).

Drawing