Protection device for a ceramic tile conveyor line

Abstract

The protection device (1) is associated with a coating head (100) from a calibrated slot (101) of which a laminar veil (V) of ceramic glaze continuously falls, which uniformly covers ceramic tiles (3), fed by a conveyor line (2) with belts (20), arranged in a row and spaced apart from each other by an empty space (K). The protection device (1) prevents the sections of belts (20) that remain uncovered in said empty spaces (K) from being soiled, by means of at least one battery (4) equipped with a number of nozzles (40) fed with compressed air equal to that of the belts (20). Said nozzles (40) are each equipped with a device (41) for instantaneous opening / closing of the jet, are facing the laminar veil (V) and are arranged above and aligned with the belts 20. By means of sensors (6), positioned upstream of the coating head (100), each empty space (K) between two consecutive ceramic tiles (3) is detected, as well as the front (3A) and rear (3P) transversal side of the same; the signals supplied by the aforementioned sensors (6) go to an electronic control unit (7), which opens, with suitable synchronism, the compressed air jet of all the nozzles (40), at the beginning of the transit of each empty space (K) under the aforementioned laminar veil (V), then, at the end, their instantaneous closure. In this phase, the air jets intercept pre-established portions (PV) of the laminar veil (V), so that they do not settle on the belts (20), but are deviated towards the sides of the latter.

Description

[0001] The present invention falls within the technical sector concerning machinery used in the ceramic industry for the decoration of ceramic tiles or slabs.

[0002] In particular, the machines taken into consideration are those that apply a uniform layer of liquid glaze on the entire upper surface, or on a part of it, of said ceramic tiles or slabs, said machines being also known as coating heads.BACKGROUND ART

[0003] A coating head essentially consists of a hopper into which the liquid glaze is fed, preferably of the so-called "in solution" type, with a calibrated outlet slot at the bottom, from which a laminar veil of said liquid glaze emerges which, by falling, is deposited on the underlying ceramic tiles or slabs in transit, arranged in an orderly succession and advanced, at a constant speed, by a rectilinear transport line.

[0004] Normally, these conveyor lines consist of two or more belts arranged parallel at pre-established transverse distances from each other, and which wind in a closed loop around their respective motorised return pulleys.

[0005] The ceramic tiles or slabs rest on the upper (tensioned) branches of said belts and are arranged in a row so that an empty longitudinal space of almost constant width is left between one and the next.

[0006] In order for the laminar glaze layer to uniformly cover the ceramic tiles or slabs, the most widely used known technique requires that once the glaze has started to fall, the laminar glaze be continuous, meaning it is not interrupted during the passage of the empty spaces between one tile and another. This is because, as industry experts know, it would be difficult to perfectly synchronize the break of the glaze flow and its resumption with the aforementioned passage of the empty spaces, due to the difficulty of obtaining both an instantaneous interruption of the laminar glaze and an equally instantaneous resumption of the flow, uniform across the entire width of the laminar glaze itself.

[0007] These problems would considerably increase the probability of having laying defects in the portions of the upper facade adjacent to the front and / or rear transverse sides of the ceramic tiles or slabs, and therefore of an increase in production waste.

[0008] The glaze continues to flow as it passes through the empty spaces between the tiles, and some of it settles on the belts, soiling them. Naturally, the machine includes a tray beneath the laminar veil, beneath the ceramic tiles in transit, and beneath the upper section of the belts, designed to collect any excess glaze that hasn't settled on the tile or belts.

[0009] As intuitively understandable, the progressive soiling of the belts represents a serious inconvenience, because it leaves traces of color on the lower faces of the subsequently transported tiles, which are unacceptable, especially in high-end ceramic products.

[0010] To overcome the aforementioned drawback, the same Applicant has developed a technical solution described in the prior document EP1815957A2, which discloses a conveyor device for transporting ceramic tiles or similar articles, mounted on an application line suitable for applying a decorative product, such as ceramic tile glaze, to the tiles using a curtain coater. The curtain coater is designed to generate a continuous glaze layer that can be spread over one face of the ceramic tiles as they are advanced by the conveyor device through the glaze layer.

[0011] The conveyor comprises an upstream conveyor branch and a downstream conveyor branch, arranged sequentially, which define a transverse space between them, corresponding to the surface where the glaze film falls. This transverse space may be perpendicular or oblique to the direction of tile advancement and may be straight or curved. Each conveyor branch comprises a plurality of narrow belts that extend in a closed loop, arranged side by side, substantially parallel to each other and at a predefined distance from each other.

[0012] This technical solution is simple and effective, but to limit the longitudinal width of the space between the two upstream and downstream branches, and to avoid vertical oscillations of the tiles during the transition from the first to the second conveyor, the belt return pulleys located in this space must be as small as possible. This requirement requires the belts to be very flexible in order to follow a narrow radius of curvature, and this inevitably reduces their ability to remain straight when burdened by the weight of the tiles.

[0013] In another previous document, identified with the number DE 102008002351 A1, a device is described for dispensing a layer of a pasty substance downwards which is deposited on a paper or similar surface in transit below.

[0014] The apparatus features a comb-type dosing roller upstream of the lower outlet slot. This roller has a plurality of adjacent annular grooves through which the paste passes by gravity from the upper chamber to the lower outlet slot. In one of the embodiments illustrated in the document, the dosing roller has grooves extending only 180°, so that in a first predetermined angular position of the dosing roller, the paste is allowed to flow, while in another angular position, such flow is prevented.

[0015] Although a technical solution such as the one proposed in the aforementioned prior document configures a sort of on / off tap for the dispensing of a substance, it does not offer technical teachings adaptable to the technical sector of the present invention, as it is not capable of solving the problems set out above with reference to the laminar veil of glaze.TECHNICAL PROBLEM

[0016] The main technical problem that the present invention intends to solve is therefore that of avoiding the soiling of the belts of a conveyor line that carry the ceramic tiles under a coating head, by proposing a protection device for said belts shaped in such a way that its operation is compatible with maintaining the continuous fall of the laminar veil.OBJECTS OF THE INVENTION

[0017] Another object of the present invention is to propose a protection device that acts on the laminar veil without the aid of moving mechanical parts and that guarantees reliable operation even in the absence of frequent maintenance.

[0018] Another object of the invention is to create a protection device shaped so as to be self-adaptive, in particular to be able to modify each individual intervention manoeuvre in real time in relation to the actual length of the empty space between one ceramic tile and another.

[0019] A further object of the invention is to obtain a protection device whose configuration can be easily customised according to the number and position of the belts that make up the ceramic tile transport line.

[0020] Another object of the invention concerns the desire to create a particularly versatile protection device, capable of being associated with both newly built coating heads and existing ones, at least those produced by the same Applicant.

[0021] Yet another object of the invention is to propose a protection device whose operation is independent from that of the respective coating head, which therefore does not require any type of mechanical or management software adaptation due to the presence of the present protection device.SUMMARY OF THE INVENTION

[0022] These and other purposes are entirely achieved by means of a protection device for a ceramic tile conveyor line, with said conveyor line of the type consisting of parallel belts, each of which is wound in a closed loop on relative pulleys, and with said ceramic tiles arranged in support on the upper branches of said belts, arranged in a row and separated from each other by an empty space, to be sent underneath a coating head, from a calibrated slot from which a laminar coating of ceramic glaze emerges continuously downwards, arranged perpendicular to the direction of advancement of the ceramic tiles and intended to deposit uniformly on their respective upper faces.

[0023] The aforementioned protection device is associated with the aforementioned coating head and includes: at least one battery of nozzles, for the emission of compressed air, with said battery arranged in proximity to the aforementioned laminar veil of glaze falling from said coating head and formed by a number of nozzles corresponding to that of the aforementioned belts, the same nozzles being arranged in such a way that each of them is above and aligned with respect to a relative belt, as well as suitably oriented so that the jet of compressed air is directed to intercept said laminar veil and a portion of the respective underlying belt; means for supplying compressed air to each of the nozzles of the aforementioned battery; an instantaneous opening / closing organ, associated in the body of each of said nozzles and intended to control or stop the emission of compressed air; sensor organs, arranged along the aforementioned conveyor line, upstream of the aforementioned coating head, designed to detect first the front transverse side and then the rear transverse side of each ceramic tile in transit, as well as the position and length of each aforementioned empty space between two respective consecutive ceramic tiles; an electronic control unit, designed to receive inputs relating to the forward speed of the aforementioned ceramic tiles on the conveyor line and the signals provided in sequence by the aforementioned sensor organs, relating to the said front and rear transverse sides of the ceramic tiles arriving towards the said coating head, the aforementioned electronic control unit being equipped with a suitable software program and algorithms capable of determining, on the basis of the inputs received, first the activation of all the aforementioned organs in the instantaneous opening position of the nozzles, then their instantaneous closing, with suitable synchronism respectively to the transit of each empty space existing in the row between one ceramic tile and the next, beneath the aforementioned laminar glaze veil, so that the air jets ejected from the aforementioned nozzles impact on the latter so that pre-established portions of the same laminar glaze veil, otherwise destined to deposit on the belts, are deviated towards the sides of the latter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The characteristic features of the present invention will be apparent from the following description of a preferred embodiment of the protection device for a ceramic tile conveyor line, according to the claims and with the aid of the attached drawing tables, wherein: Fig. 1 shows, in a schematic front view, a coating head to which the protection device of the invention is associated, in a preferred embodiment, with the coating head associated with a belt conveyor line on which ceramic tiles are carried, in the phase in which a homogeneous layer of glaze dispensed by the coating head itself is deposited on the latter; Fig. 2 shows, in a view similar to Fig. 1, the operational phase of the protection device which intervenes during the transit under the coating head of the empty space which longitudinally separates one ceramic tile from another, to avoid dirtying the belts of the conveyor line; Fig. 3A shows a view along the section plane III-III of Fig. 1, in which a sensor organ of the protection device detects the limit of the rear transverse side of a ceramic tile; Fig. 3B shows another view along the section plane III-III of Fig. 1, where said sensor organ detects the limit of the front transverse side of a following ceramic tile; Fig. 4A shows a view along the section plane IV-IV of Fig. 2, in which the protection device is activated in its operating phase to divert portions of the laminar glaze veil in correspondence with the belts, in synchrony with the start of the passage under the coating head of an empty space between two consecutive ceramic tiles; Fig. 4B shows another view along the section plane IV-IV of Fig. 2, in which the protection device is deactivated in synchrony with the end of the passage under the coating head of said empty space between the two consecutive ceramic tiles. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0025] In the above figures, the protection device for a ceramic tile conveyor line 2 3, which is the object of the present invention, has been indicated as a whole with reference 1.

[0026] In a manner known per se, said conveyor line 2 is of the type made up of at least two parallel belts 20, or four as illustrated in the non-limiting example in the attached Figs. 1 and 2.

[0027] The number of belts 20 and their transverse distance are evidently a function of the size of the ceramic tiles 3 to be transported.

[0028] Each of the aforementioned belts 20 is wound in a closed loop on relative pulleys 21, of which the front one is keyed onto a shaft 22 together with the corresponding front pulleys 21 of the remaining belts 20 to be driven in synchrony by motor components 23.

[0029] In this way, the upper branches 20S of the belts 20 remain taut and are suitable for supporting, for transport, the ceramic tiles 3, which are arranged in a row and detached from each other, to be sent under a known coating head 100, for example like the one illustrated in the figures and produced by the same Applicant.

[0030] Therefore, between two consecutive ceramic tiles 3 there is an empty space K of longitudinal width preferably, although not necessarily, always equal or almost equal.

[0031] From a calibrated slot 101 of the coating head 100, a laminar veil V of ceramic glaze emerges continuously downwards, arranged perpendicularly to a forward direction X of the ceramic tiles 3 and intended to deposit uniformly on their respective upper face 3S.

[0032] In order to ensure that the thickness of the glaze deposited on the upper face 3S of the ceramic tiles 3 is constant, the conveyor line 2 is operated at a constant speed.

[0033] According to an embodiment of the invention, the protection device 1 comprises means 4 for dispensing jets of compressed air, in turn comprising at least one set of nozzles 40, arranged in proximity to the aforementioned laminar layer V of glaze, and made up of a number of nozzles 40 corresponding to that of the aforementioned belts 20.

[0034] According to a variant of the invention, the nozzles 40 are provided both upstream and downstream of the glaze veil V.

[0035] The nozzles 40 are designed to emit synchronized jets of compressed air, upon command of respective instantaneous opening / closing devices 41, associated in the body of each of the nozzles 40.

[0036] Each instantaneous opening / closing device 41 of a nozzle 40 is constituted, in a possible but not exclusive embodiment, by an electromechanically operated needle valve, of a substantially known type and therefore not illustrated in detail.

[0037] The nozzles 40 are arranged in such a way that each of them is above and aligned with respect to a relative belt 20, as well as suitably oriented so that the jet of compressed air is directed to intercept said laminar veil V and a portion of the respective belt 20 below.

[0038] More precisely, the jet of compressed air emitted by each of the aforementioned nozzles 40 has a conical shape, with a pre-established opening angle and with the median vertical plane of the emission cone 40C of the air jet substantially coplanar with the plane of the respective belt 20.

[0039] Furthermore, each of said nozzles 40 has, on said median vertical plane, an orientation of the axis of the aforementioned emission cone 40C inclined with respect to the forward direction X of said transport line 2, such that the ejected compressed air is directed substantially grazing the underlying belts 20.

[0040] The inclination of the axes of the nozzles 40 will be subject to adjustment for each specific installation on a coating head 100, however it is possible to say that it is preferably an acute angle, not exceeding 45°.

[0041] The protection device 1 also comprises means 5 for supplying compressed air to each of the nozzles 40 of the battery 4; said means 5 have not been illustrated in detail as they are mostly made up of known types of organs and components, and have been shown as a block in Figs. 1 and 2. The compressed air is conveniently supplied by generating means, consisting of a compressor arranged locally, or a central compressor equipped with pipes suitable for conveying the compressed air produced.

[0042] Such supply means 5 advantageously includes a common supply duct 50 for the compressed air, mounted on the coating head 100 in a horizontal position and substantially parallel to that of the aforementioned laminar veil V of glaze.

[0043] The predetermined number of nozzles 40 of the nozzle bank 4 are associated with the common duct 50, with the expected transverse spacing.

[0044] The common duct 50 is kept under pressure, for reasons that will become more apparent later.

[0045] The protection device 1 includes sensors 6, for example of an optical or laser type, arranged along the aforementioned conveyor line 2, upstream of the aforementioned coating head 100, designed to detect first the front transverse side 3A and subsequently the rear transverse side 3P of each ceramic tile 3 in transit and, consequently, the position and length of each empty space K between two consecutive ceramic tiles 3.

[0046] The protection device 1 also comprises an electronic control unit 7, designed to receive inputs relating to the forward speed of the aforementioned ceramic tiles 3 on the conveyor line 2 and the signals supplied in sequence by the aforementioned sensors 6, relating to the said front 3A and rear 3P transverse sides of the ceramic tiles 3 arriving towards the aforementioned coating head 100, as well as towards the laminar glaze veil V which exits from the latter.

[0047] The electronic control unit 7 is equipped with a suitable software program and algorithms capable of determining, based on the input received, first the activation of all the aforementioned devices 41 in the instantaneous opening position of the nozzles 40, then their instantaneous closing, as better described below.

[0048] The embodiment (not illustrated) of the protection device 1 described up to now provides for a single battery 4 of nozzles 40, with the latter arranged, for example but not necessarily, in such a way that the compressed air ejected from each of them is directed in the same direction as the advancement direction X of the ceramic tiles 3 on the transport line 2.

[0049] In a different, preferred embodiment of the protection device 1, illustrated in the figures, two of said batteries 4 of nozzles 40 are advantageously provided, respectively first 4F and second 4R, arranged respectively upstream and downstream of the glaze layer V, one opposite the other and symmetrically arranged with respect to the same layer V, so that the compressed air emitted by the aforementioned first battery 4F is directed in the same direction as that of advancement X of the ceramic tiles 3 on the transport line 2, while the compressed air emitted by the second battery 4R is directed in the opposite direction.

[0050] According to this latter preferred embodiment, the supply means 5 comprise (see figures 3A, 3B) an upstream duct 50M for supplying compressed air, supporting the first battery of nozzles 4F and mounted on the coating head 100 upstream of the glaze layer V, and a downstream duct 40V, supporting the second battery of nozzles 4R and mounted on the coating head 100 downstream of the glaze layer V.

[0051] The trim adjustments that concern each pair of opposing nozzles 40 of the said two batteries, first 4F and second 4R, without prejudice to the previous general indications, are implemented to ensure that the cross flow of the respective compressed air jets causes the deviation of a corresponding portion PV of the laminar veil V of glaze having a triangular shape with its vertex at the top (Fig. 2).

[0052] The operation of the proposed protection device 1 is now described, in the preferred embodiment just described, starting from an operating situation such as the one illustrated in Fig. 1, in which a generic first ceramic tile 3 is passing through the laminar layer V of glaze, which is deposited on its upper face 3S.

[0053] In this situation the aforementioned instantaneous opening / closing devices 41 keep the nozzles 40 closed, while the supply means 5 keep the ducts 50M,50V of each battery 4F, 4R of nozzles 40 under pressure.

[0054] The advancement of the first ceramic tile 3 brings the rear transverse side 3P of the latter to coincide with the ray emitted by the sensors 6, which detects its passage (Fig. 3A).

[0055] The sensors 6, after having detected the complete transit of the empty space K between said first ceramic tile 3 and a second ceramic tile 3 which follows, intercept the passage of the front transverse side 3A of the latter (Fig. 3B).

[0056] Using the data supplied by the sensors 6 to the electronic control unit 7, and knowing the parameters relating to the advancement speed of the transport line 2, the time required to bring the rear transverse side 3P of the first ceramic tile 3 to coincide with the plane on which the laminar layer V of glaze falls is calculated.

[0057] At the precise moment in which the aforementioned alignment occurs, the devices 41 are activated simultaneously so that all the nozzles 40 are opened and spray compressed air, so that the air jets impact on said laminar veil V, so that pre-established portions PV of the latter, otherwise destined to deposit on the belts 20, are deviated towards the sides of the latter (Fig. 4A).

[0058] As previously stated, the cross-flow of the opposing compressed air jets coming from the nozzles 40 of the two batteries 4F, 4R, requires the deviation of a corresponding portion PV of the laminar glaze layer V, having a triangular shape with the vertex at the top, for each of the belts 20 present (see again Fig. 2).

[0059] The electronic control unit 7, by means of the corresponding software, has previously determined the time for maintaining the nozzles 40 open, which is needed to allow the entire empty space K between the first and second ceramic tile 3 to pass through (Fig. 4B), during which, as stated above, the portions PV of the laminar veil V are deviated so as not to dirty the belts 20.

[0060] In synchronism with the arrival of the front transverse side 3A of the second ceramic tile 3 to coincide with the plane on which the laminar layer V of glaze falls, the opening / closing devices 41 of the nozzles 40 are simultaneously closed, which cease to emit compressed air, allowing the instantaneous restoration of the integrity of the laminar layer V of glaze falling from the calibrated slot 101 (see again Fig. 1).

[0061] The operating phases of the protection device 1, described above, are replicated in sequence for the following ceramic tiles 3: it is important to highlight how the precise detection of each empty space K that is about to cross the laminar web V, in relation to its longitudinal development and its position along the conveyor line 2, advantageously allows for perfect synchronism in real time so as not to dirty the belts 20, even if the width of the empty space K and / or the length of the various ceramic tiles 3 arranged on the conveyor line 2 varies.

[0062] According to a further embodiment of the protection device 1, not illustrated as it is immediately understandable, the above-mentioned compressed air delivery means 4 are constituted by a plurality of calibrated holes, made in the common duct 50, or in the upstream ducts 50M and downstream ducts 50V in the case of a variant embodiment of the invention corresponding to the one already described previously. The calibrated holes are, like the already described nozzles 40 of the preferred embodiment, in a number equal to the belts 20, and are arranged in such a way that each of them is above and aligned with respect to a relative belt 20, so that the jet of compressed air supplied by them is directed to intercept the laminar layer V of glaze, to divert its path outside the belts 20. In the case in which the upstream ducts 50M and the downstream ducts 50V are provided, the corresponding calibrated holes of the two ducts 50M,50V are opposite each other and aligned vertically with respect to the corresponding aforementioned belt (20).

[0063] From the preceding description, the peculiar characteristics of the protection device proposed with the present invention clearly emerge, which allow for the effective resolution of the technical problem posed, preventing the soiling of the belts of a ceramic tile transport line when the empty spaces between the ceramic tiles themselves pass under a coating head.

[0064] The laminar veil of glaze is then hit by jets of compressed air that instantly deflect it, preventing it from settling on the exposed belts in the empty space between tiles. When the air flow ceases, just as instantly, the laminar veil recomposes itself and begins to evenly cover the incoming tile.

[0065] Therefore, the protection device is advantageously shaped so that none of its mechanical parts come into physical contact with the laminar glaze veil or interfere with the functioning of the relevant coating head.

[0066] The absence of moving mechanical parts in the protection device that could come into contact with the glaze ensures reliable operation even in the absence of frequent cleaning and maintenance.

[0067] A very important aspect of the proposed protection device concerns its ability to be self-adaptive, in particular to be able to modify each individual intervention maneuver in real time in relation to the actual length of the empty space between one ceramic tile and another and / or the actual length of each of them.

[0068] As you can easily imagine, the protection device can be easily customized by adapting the number and position of the nozzles to those of the belts that make up the relevant conveyor line.

[0069] The simplicity of construction of the proposed protection device makes it particularly versatile and therefore capable of being associated with both newly built and existing coating heads, at least those produced by the same Applicant.

[0070] In addition to the ease of mechanical assembly of the protection device on the respective coating head, it is important to underline that, advantageously, no adaptation of the coating head management software is required.

[0071] However, it is understood that the above description has an exemplifying and non-limiting value, therefore any variations in detail that may be necessary for technical and / or functional reasons are considered from now on to fall within the same scope of protection defined by the claims reported below.

Examples

Embodiment Construction

[0025]In the above figures, the protection device for a ceramic tile conveyor line 2 3, which is the object of the present invention, has been indicated as a whole with reference 1.

[0026]In a manner known per se, said conveyor line 2 is of the type made up of at least two parallel belts 20, or four as illustrated in the non-limiting example in the attached Figs. 1 and 2.

[0027]The number of belts 20 and their transverse distance are evidently a function of the size of the ceramic tiles 3 to be transported.

[0028]Each of the aforementioned belts 20 is wound in a closed loop on relative pulleys 21, of which the front one is keyed onto a shaft 22 together with the corresponding front pulleys 21 of the remaining belts 20 to be driven in synchrony by motor components 23.

[0029]In this way, the upper branches 20S of the belts 20 remain taut and are suitable for supporting, for transport, the ceramic tiles 3, which are arranged in a row and detached from each other, to be sent under a known c...

[0001] The present invention falls within the technical sector concerning machinery used in the ceramic industry for the decoration of ceramic tiles or slabs.

[0002] In particular, the machines taken into consideration are those that apply a uniform layer of liquid glaze on the entire upper surface, or on a part of it, of said ceramic tiles or slabs, said machines being also known as coating heads.BACKGROUND ART

[0003] A coating head essentially consists of a hopper into which the liquid glaze is fed, preferably of the so-called "in solution" type, with a calibrated outlet slot at the bottom, from which a laminar veil of said liquid glaze emerges which, by falling, is deposited on the underlying ceramic tiles or slabs in transit, arranged in an orderly succession and advanced, at a constant speed, by a rectilinear transport line.

[0004] Normally, these conveyor lines consist of two or more belts arranged parallel at pre-established transverse distances from each other, and which wind in a closed loop around their respective motorised return pulleys.

[0005] The ceramic tiles or slabs rest on the upper (tensioned) branches of said belts and are arranged in a row so that an empty longitudinal space of almost constant width is left between one and the next.

[0006] In order for the laminar glaze layer to uniformly cover the ceramic tiles or slabs, the most widely used known technique requires that once the glaze has started to fall, the laminar glaze be continuous, meaning it is not interrupted during the passage of the empty spaces between one tile and another. This is because, as industry experts know, it would be difficult to perfectly synchronize the break of the glaze flow and its resumption with the aforementioned passage of the empty spaces, due to the difficulty of obtaining both an instantaneous interruption of the laminar glaze and an equally instantaneous resumption of the flow, uniform across the entire width of the laminar glaze itself.

[0007] These problems would considerably increase the probability of having laying defects in the portions of the upper facade adjacent to the front and / or rear transverse sides of the ceramic tiles or slabs, and therefore of an increase in production waste.

[0008] The glaze continues to flow as it passes through the empty spaces between the tiles, and some of it settles on the belts, soiling them. Naturally, the machine includes a tray beneath the laminar veil, beneath the ceramic tiles in transit, and beneath the upper section of the belts, designed to collect any excess glaze that hasn't settled on the tile or belts.

[0009] As intuitively understandable, the progressive soiling of the belts represents a serious inconvenience, because it leaves traces of color on the lower faces of the subsequently transported tiles, which are unacceptable, especially in high-end ceramic products.

[0010] To overcome the aforementioned drawback, the same Applicant has developed a technical solution described in the prior document EP1815957A2, which discloses a conveyor device for transporting ceramic tiles or similar articles, mounted on an application line suitable for applying a decorative product, such as ceramic tile glaze, to the tiles using a curtain coater. The curtain coater is designed to generate a continuous glaze layer that can be spread over one face of the ceramic tiles as they are advanced by the conveyor device through the glaze layer.

[0011] The conveyor comprises an upstream conveyor branch and a downstream conveyor branch, arranged sequentially, which define a transverse space between them, corresponding to the surface where the glaze film falls. This transverse space may be perpendicular or oblique to the direction of tile advancement and may be straight or curved. Each conveyor branch comprises a plurality of narrow belts that extend in a closed loop, arranged side by side, substantially parallel to each other and at a predefined distance from each other.

[0012] This technical solution is simple and effective, but to limit the longitudinal width of the space between the two upstream and downstream branches, and to avoid vertical oscillations of the tiles during the transition from the first to the second conveyor, the belt return pulleys located in this space must be as small as possible. This requirement requires the belts to be very flexible in order to follow a narrow radius of curvature, and this inevitably reduces their ability to remain straight when burdened by the weight of the tiles.

[0013] In another previous document, identified with the number DE 102008002351 A1, a device is described for dispensing a layer of a pasty substance downwards which is deposited on a paper or similar surface in transit below.

[0014] The apparatus features a comb-type dosing roller upstream of the lower outlet slot. This roller has a plurality of adjacent annular grooves through which the paste passes by gravity from the upper chamber to the lower outlet slot. In one of the embodiments illustrated in the document, the dosing roller has grooves extending only 180°, so that in a first predetermined angular position of the dosing roller, the paste is allowed to flow, while in another angular position, such flow is prevented.

[0015] Although a technical solution such as the one proposed in the aforementioned prior document configures a sort of on / off tap for the dispensing of a substance, it does not offer technical teachings adaptable to the technical sector of the present invention, as it is not capable of solving the problems set out above with reference to the laminar veil of glaze.TECHNICAL PROBLEM

[0016] The main technical problem that the present invention intends to solve is therefore that of avoiding the soiling of the belts of a conveyor line that carry the ceramic tiles under a coating head, by proposing a protection device for said belts shaped in such a way that its operation is compatible with maintaining the continuous fall of the laminar veil.OBJECTS OF THE INVENTION

[0017] Another object of the present invention is to propose a protection device that acts on the laminar veil without the aid of moving mechanical parts and that guarantees reliable operation even in the absence of frequent maintenance.

[0018] Another object of the invention is to create a protection device shaped so as to be self-adaptive, in particular to be able to modify each individual intervention manoeuvre in real time in relation to the actual length of the empty space between one ceramic tile and another.

[0019] A further object of the invention is to obtain a protection device whose configuration can be easily customised according to the number and position of the belts that make up the ceramic tile transport line.

[0020] Another object of the invention concerns the desire to create a particularly versatile protection device, capable of being associated with both newly built coating heads and existing ones, at least those produced by the same Applicant.

[0021] Yet another object of the invention is to propose a protection device whose operation is independent from that of the respective coating head, which therefore does not require any type of mechanical or management software adaptation due to the presence of the present protection device.SUMMARY OF THE INVENTION

[0022] These and other purposes are entirely achieved by means of a protection device for a ceramic tile conveyor line, with said conveyor line of the type consisting of parallel belts, each of which is wound in a closed loop on relative pulleys, and with said ceramic tiles arranged in support on the upper branches of said belts, arranged in a row and separated from each other by an empty space, to be sent underneath a coating head, from a calibrated slot from which a laminar coating of ceramic glaze emerges continuously downwards, arranged perpendicular to the direction of advancement of the ceramic tiles and intended to deposit uniformly on their respective upper faces.

[0023] The aforementioned protection device is associated with the aforementioned coating head and includes: at least one battery of nozzles, for the emission of compressed air, with said battery arranged in proximity to the aforementioned laminar veil of glaze falling from said coating head and formed by a number of nozzles corresponding to that of the aforementioned belts, the same nozzles being arranged in such a way that each of them is above and aligned with respect to a relative belt, as well as suitably oriented so that the jet of compressed air is directed to intercept said laminar veil and a portion of the respective underlying belt; means for supplying compressed air to each of the nozzles of the aforementioned battery; an instantaneous opening / closing organ, associated in the body of each of said nozzles and intended to control or stop the emission of compressed air; sensor organs, arranged along the aforementioned conveyor line, upstream of the aforementioned coating head, designed to detect first the front transverse side and then the rear transverse side of each ceramic tile in transit, as well as the position and length of each aforementioned empty space between two respective consecutive ceramic tiles; an electronic control unit, designed to receive inputs relating to the forward speed of the aforementioned ceramic tiles on the conveyor line and the signals provided in sequence by the aforementioned sensor organs, relating to the said front and rear transverse sides of the ceramic tiles arriving towards the said coating head, the aforementioned electronic control unit being equipped with a suitable software program and algorithms capable of determining, on the basis of the inputs received, first the activation of all the aforementioned organs in the instantaneous opening position of the nozzles, then their instantaneous closing, with suitable synchronism respectively to the transit of each empty space existing in the row between one ceramic tile and the next, beneath the aforementioned laminar glaze veil, so that the air jets ejected from the aforementioned nozzles impact on the latter so that pre-established portions of the same laminar glaze veil, otherwise destined to deposit on the belts, are deviated towards the sides of the latter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The characteristic features of the present invention will be apparent from the following description of a preferred embodiment of the protection device for a ceramic tile conveyor line, according to the claims and with the aid of the attached drawing tables, wherein: Fig. 1 shows, in a schematic front view, a coating head to which the protection device of the invention is associated, in a preferred embodiment, with the coating head associated with a belt conveyor line on which ceramic tiles are carried, in the phase in which a homogeneous layer of glaze dispensed by the coating head itself is deposited on the latter; Fig. 2 shows, in a view similar to Fig. 1, the operational phase of the protection device which intervenes during the transit under the coating head of the empty space which longitudinally separates one ceramic tile from another, to avoid dirtying the belts of the conveyor line; Fig. 3A shows a view along the section plane III-III of Fig. 1, in which a sensor organ of the protection device detects the limit of the rear transverse side of a ceramic tile; Fig. 3B shows another view along the section plane III-III of Fig. 1, where said sensor organ detects the limit of the front transverse side of a following ceramic tile; Fig. 4A shows a view along the section plane IV-IV of Fig. 2, in which the protection device is activated in its operating phase to divert portions of the laminar glaze veil in correspondence with the belts, in synchrony with the start of the passage under the coating head of an empty space between two consecutive ceramic tiles; Fig. 4B shows another view along the section plane IV-IV of Fig. 2, in which the protection device is deactivated in synchrony with the end of the passage under the coating head of said empty space between the two consecutive ceramic tiles. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0025] In the above figures, the protection device for a ceramic tile conveyor line 2 3, which is the object of the present invention, has been indicated as a whole with reference 1.

[0026] In a manner known per se, said conveyor line 2 is of the type made up of at least two parallel belts 20, or four as illustrated in the non-limiting example in the attached Figs. 1 and 2.

[0027] The number of belts 20 and their transverse distance are evidently a function of the size of the ceramic tiles 3 to be transported.

[0028] Each of the aforementioned belts 20 is wound in a closed loop on relative pulleys 21, of which the front one is keyed onto a shaft 22 together with the corresponding front pulleys 21 of the remaining belts 20 to be driven in synchrony by motor components 23.

[0029] In this way, the upper branches 20S of the belts 20 remain taut and are suitable for supporting, for transport, the ceramic tiles 3, which are arranged in a row and detached from each other, to be sent under a known coating head 100, for example like the one illustrated in the figures and produced by the same Applicant.

[0030] Therefore, between two consecutive ceramic tiles 3 there is an empty space K of longitudinal width preferably, although not necessarily, always equal or almost equal.

[0031] From a calibrated slot 101 of the coating head 100, a laminar veil V of ceramic glaze emerges continuously downwards, arranged perpendicularly to a forward direction X of the ceramic tiles 3 and intended to deposit uniformly on their respective upper face 3S.

[0032] In order to ensure that the thickness of the glaze deposited on the upper face 3S of the ceramic tiles 3 is constant, the conveyor line 2 is operated at a constant speed.

[0033] According to an embodiment of the invention, the protection device 1 comprises means 4 for dispensing jets of compressed air, in turn comprising at least one set of nozzles 40, arranged in proximity to the aforementioned laminar layer V of glaze, and made up of a number of nozzles 40 corresponding to that of the aforementioned belts 20.

[0034] According to a variant of the invention, the nozzles 40 are provided both upstream and downstream of the glaze veil V.

[0035] The nozzles 40 are designed to emit synchronized jets of compressed air, upon command of respective instantaneous opening / closing devices 41, associated in the body of each of the nozzles 40.

[0036] Each instantaneous opening / closing device 41 of a nozzle 40 is constituted, in a possible but not exclusive embodiment, by an electromechanically operated needle valve, of a substantially known type and therefore not illustrated in detail.

[0037] The nozzles 40 are arranged in such a way that each of them is above and aligned with respect to a relative belt 20, as well as suitably oriented so that the jet of compressed air is directed to intercept said laminar veil V and a portion of the respective belt 20 below.

[0038] More precisely, the jet of compressed air emitted by each of the aforementioned nozzles 40 has a conical shape, with a pre-established opening angle and with the median vertical plane of the emission cone 40C of the air jet substantially coplanar with the plane of the respective belt 20.

[0039] Furthermore, each of said nozzles 40 has, on said median vertical plane, an orientation of the axis of the aforementioned emission cone 40C inclined with respect to the forward direction X of said transport line 2, such that the ejected compressed air is directed substantially grazing the underlying belts 20.

[0040] The inclination of the axes of the nozzles 40 will be subject to adjustment for each specific installation on a coating head 100, however it is possible to say that it is preferably an acute angle, not exceeding 45°.

[0041] The protection device 1 also comprises means 5 for supplying compressed air to each of the nozzles 40 of the battery 4; said means 5 have not been illustrated in detail as they are mostly made up of known types of organs and components, and have been shown as a block in Figs. 1 and 2. The compressed air is conveniently supplied by generating means, consisting of a compressor arranged locally, or a central compressor equipped with pipes suitable for conveying the compressed air produced.

[0042] Such supply means 5 advantageously includes a common supply duct 50 for the compressed air, mounted on the coating head 100 in a horizontal position and substantially parallel to that of the aforementioned laminar veil V of glaze.

[0043] The predetermined number of nozzles 40 of the nozzle bank 4 are associated with the common duct 50, with the expected transverse spacing.

[0044] The common duct 50 is kept under pressure, for reasons that will become more apparent later.

[0045] The protection device 1 includes sensors 6, for example of an optical or laser type, arranged along the aforementioned conveyor line 2, upstream of the aforementioned coating head 100, designed to detect first the front transverse side 3A and subsequently the rear transverse side 3P of each ceramic tile 3 in transit and, consequently, the position and length of each empty space K between two consecutive ceramic tiles 3.

[0046] The protection device 1 also comprises an electronic control unit 7, designed to receive inputs relating to the forward speed of the aforementioned ceramic tiles 3 on the conveyor line 2 and the signals supplied in sequence by the aforementioned sensors 6, relating to the said front 3A and rear 3P transverse sides of the ceramic tiles 3 arriving towards the aforementioned coating head 100, as well as towards the laminar glaze veil V which exits from the latter.

[0047] The electronic control unit 7 is equipped with a suitable software program and algorithms capable of determining, based on the input received, first the activation of all the aforementioned devices 41 in the instantaneous opening position of the nozzles 40, then their instantaneous closing, as better described below.

[0048] The embodiment (not illustrated) of the protection device 1 described up to now provides for a single battery 4 of nozzles 40, with the latter arranged, for example but not necessarily, in such a way that the compressed air ejected from each of them is directed in the same direction as the advancement direction X of the ceramic tiles 3 on the transport line 2.

[0049] In a different, preferred embodiment of the protection device 1, illustrated in the figures, two of said batteries 4 of nozzles 40 are advantageously provided, respectively first 4F and second 4R, arranged respectively upstream and downstream of the glaze layer V, one opposite the other and symmetrically arranged with respect to the same layer V, so that the compressed air emitted by the aforementioned first battery 4F is directed in the same direction as that of advancement X of the ceramic tiles 3 on the transport line 2, while the compressed air emitted by the second battery 4R is directed in the opposite direction.

[0050] According to this latter preferred embodiment, the supply means 5 comprise (see figures 3A, 3B) an upstream duct 50M for supplying compressed air, supporting the first battery of nozzles 4F and mounted on the coating head 100 upstream of the glaze layer V, and a downstream duct 40V, supporting the second battery of nozzles 4R and mounted on the coating head 100 downstream of the glaze layer V.

[0051] The trim adjustments that concern each pair of opposing nozzles 40 of the said two batteries, first 4F and second 4R, without prejudice to the previous general indications, are implemented to ensure that the cross flow of the respective compressed air jets causes the deviation of a corresponding portion PV of the laminar veil V of glaze having a triangular shape with its vertex at the top (Fig. 2).

[0052] The operation of the proposed protection device 1 is now described, in the preferred embodiment just described, starting from an operating situation such as the one illustrated in Fig. 1, in which a generic first ceramic tile 3 is passing through the laminar layer V of glaze, which is deposited on its upper face 3S.

[0053] In this situation the aforementioned instantaneous opening / closing devices 41 keep the nozzles 40 closed, while the supply means 5 keep the ducts 50M,50V of each battery 4F, 4R of nozzles 40 under pressure.

[0054] The advancement of the first ceramic tile 3 brings the rear transverse side 3P of the latter to coincide with the ray emitted by the sensors 6, which detects its passage (Fig. 3A).

[0055] The sensors 6, after having detected the complete transit of the empty space K between said first ceramic tile 3 and a second ceramic tile 3 which follows, intercept the passage of the front transverse side 3A of the latter (Fig. 3B).

[0056] Using the data supplied by the sensors 6 to the electronic control unit 7, and knowing the parameters relating to the advancement speed of the transport line 2, the time required to bring the rear transverse side 3P of the first ceramic tile 3 to coincide with the plane on which the laminar layer V of glaze falls is calculated.

[0057] At the precise moment in which the aforementioned alignment occurs, the devices 41 are activated simultaneously so that all the nozzles 40 are opened and spray compressed air, so that the air jets impact on said laminar veil V, so that pre-established portions PV of the latter, otherwise destined to deposit on the belts 20, are deviated towards the sides of the latter (Fig. 4A).

[0058] As previously stated, the cross-flow of the opposing compressed air jets coming from the nozzles 40 of the two batteries 4F, 4R, requires the deviation of a corresponding portion PV of the laminar glaze layer V, having a triangular shape with the vertex at the top, for each of the belts 20 present (see again Fig. 2).

[0059] The electronic control unit 7, by means of the corresponding software, has previously determined the time for maintaining the nozzles 40 open, which is needed to allow the entire empty space K between the first and second ceramic tile 3 to pass through (Fig. 4B), during which, as stated above, the portions PV of the laminar veil V are deviated so as not to dirty the belts 20.

[0060] In synchronism with the arrival of the front transverse side 3A of the second ceramic tile 3 to coincide with the plane on which the laminar layer V of glaze falls, the opening / closing devices 41 of the nozzles 40 are simultaneously closed, which cease to emit compressed air, allowing the instantaneous restoration of the integrity of the laminar layer V of glaze falling from the calibrated slot 101 (see again Fig. 1).

[0061] The operating phases of the protection device 1, described above, are replicated in sequence for the following ceramic tiles 3: it is important to highlight how the precise detection of each empty space K that is about to cross the laminar web V, in relation to its longitudinal development and its position along the conveyor line 2, advantageously allows for perfect synchronism in real time so as not to dirty the belts 20, even if the width of the empty space K and / or the length of the various ceramic tiles 3 arranged on the conveyor line 2 varies.

[0062] According to a further embodiment of the protection device 1, not illustrated as it is immediately understandable, the above-mentioned compressed air delivery means 4 are constituted by a plurality of calibrated holes, made in the common duct 50, or in the upstream ducts 50M and downstream ducts 50V in the case of a variant embodiment of the invention corresponding to the one already described previously. The calibrated holes are, like the already described nozzles 40 of the preferred embodiment, in a number equal to the belts 20, and are arranged in such a way that each of them is above and aligned with respect to a relative belt 20, so that the jet of compressed air supplied by them is directed to intercept the laminar layer V of glaze, to divert its path outside the belts 20. In the case in which the upstream ducts 50M and the downstream ducts 50V are provided, the corresponding calibrated holes of the two ducts 50M,50V are opposite each other and aligned vertically with respect to the corresponding aforementioned belt (20).

[0063] From the preceding description, the peculiar characteristics of the protection device proposed with the present invention clearly emerge, which allow for the effective resolution of the technical problem posed, preventing the soiling of the belts of a ceramic tile transport line when the empty spaces between the ceramic tiles themselves pass under a coating head.

[0064] The laminar veil of glaze is then hit by jets of compressed air that instantly deflect it, preventing it from settling on the exposed belts in the empty space between tiles. When the air flow ceases, just as instantly, the laminar veil recomposes itself and begins to evenly cover the incoming tile.

[0065] Therefore, the protection device is advantageously shaped so that none of its mechanical parts come into physical contact with the laminar glaze veil or interfere with the functioning of the relevant coating head.

[0066] The absence of moving mechanical parts in the protection device that could come into contact with the glaze ensures reliable operation even in the absence of frequent cleaning and maintenance.

[0067] A very important aspect of the proposed protection device concerns its ability to be self-adaptive, in particular to be able to modify each individual intervention maneuver in real time in relation to the actual length of the empty space between one ceramic tile and another and / or the actual length of each of them.

[0068] As you can easily imagine, the protection device can be easily customized by adapting the number and position of the nozzles to those of the belts that make up the relevant conveyor line.

[0069] The simplicity of construction of the proposed protection device makes it particularly versatile and therefore capable of being associated with both newly built and existing coating heads, at least those produced by the same Applicant.

[0070] In addition to the ease of mechanical assembly of the protection device on the respective coating head, it is important to underline that, advantageously, no adaptation of the coating head management software is required.

[0071] However, it is understood that the above description has an exemplifying and non-limiting value, therefore any variations in detail that may be necessary for technical and / or functional reasons are considered from now on to fall within the same scope of protection defined by the claims reported below.

Examples

Embodiment Construction

[0025]In the above figures, the protection device for a ceramic tile conveyor line 2 3, which is the object of the present invention, has been indicated as a whole with reference 1.

[0026]In a manner known per se, said conveyor line 2 is of the type made up of at least two parallel belts 20, or four as illustrated in the non-limiting example in the attached Figs. 1 and 2.

[0027]The number of belts 20 and their transverse distance are evidently a function of the size of the ceramic tiles 3 to be transported.

[0028]Each of the aforementioned belts 20 is wound in a closed loop on relative pulleys 21, of which the front one is keyed onto a shaft 22 together with the corresponding front pulleys 21 of the remaining belts 20 to be driven in synchrony by motor components 23.

[0029]In this way, the upper branches 20S of the belts 20 remain taut and are suitable for supporting, for transport, the ceramic tiles 3, which are arranged in a row and detached from each other, to be sent under a known c...

Claims

1. Protection device for a ceramic tile conveyor line, said conveyor line (2) comprising parallel belts (20), each of which being wound in a closed loop on relative pulleys (21), and with said ceramic tiles (3) being arranged to rest on the upper branches (20S) of said belts (20), arranged in a row and separated from each other by an empty space (K), to be sent under a coating head (100), from a calibrated slot (101) from which a laminar veil (V) of ceramic glaze emerges downwards continuously, arranged transversally with respect to the direction of advancement (X) of the ceramic tiles (3) and intended to settle uniformly on their respective upper face (3S), said protection device (1) being characterised in that it comprises: - means (4) for dispensing jets of compressed air, fixed to said coating head (100) above the aforementioned belts (20) and in vertical alignment with the same, capable of emitting on command jets of compressed toward said veil (V), in phase relationship with the transit of said tiles (3), to deviate it laterally in correspondence with the same belts (20) and prevent contamination of the latter by the ceramic glaze; - means (5) supplying compressed air to said dispensing means (4), with the interposition of instantaneous opening / closing devices (41), intended to stop or activate the emission of compressed air, respectively in correspondence with the presence of the aforementioned tiles (3) under the veil (V) and in their absence; - sensors (6), arranged along the aforementioned transport line (2), upstream of the aforementioned coating head (100), designed to detect first the front transverse side (3A) and subsequently the rear transverse side (3P) of each ceramic tile (3) in transit, as well as the position and length of each aforementioned empty space (K) between two respective consecutive ceramic tiles (3); - an electronic control unit (7), designed to receive inputs relating to the forward speed of the aforementioned ceramic tiles (3) on the transport line (2) and the signals supplied in sequence by the aforementioned sensors (6), and consequently command the stopping of the compressed air supply, in correspondence with the passage of a tile (3), and the activation of the supply in the absence of the same.

2. Protection device according to claim 1, characterised in that said dispensing means (4) comprises at least one set of nozzles (40), arranged near the aforementioned laminar veil (V) of glaze falling from said coating head (100) in a number of nozzles (40) corresponding to that of the aforementioned belts (20), the same nozzles (40) being arranged in such a way that each of them is above and aligned with respect to a relative belt (20), as well as suitably oriented so that the jet of compressed air is directed to intercept said laminar veil (V).

3. Protection device according to claim 2, characterised in that two of said nozzle banks (40) are provided, one opposite the other and symmetrically arranged with respect to the aforementioned laminar layer (V) of glaze, so that the compressed air emitted by a first bank (4F) of nozzles (40) is directed in the same direction as the advancement (X) of the aforementioned ceramic tiles (3) on the transport line (2), while the compressed air from the remaining bank (4R) is directed in the opposite direction.

4. Protection device according to claim 2, characterised in that the aforementioned means (5) for supplying compressed air to the nozzles (40) comprise a common supply duct (50) for the compressed air, supporting said nozzles (40) and mounted on the coating head (100) with a horizontal arrangement and substantially parallel to that of the aforementioned laminar veil (V) of glaze, said common duct (50) being associated with the pre-established number of nozzles (40), with the foreseen transverse spacing.

5. Protection device according to claim 3, characterised in that the aforementioned means (5) for supplying compressed air to the nozzles (40) comprises an upstream duct (50M) for supplying compressed air, supporting said first battery of nozzles (4F) and mounted on the coating head (100) upstream of said glaze veil (V), and a downstream duct (50V), supporting said second battery of nozzles (4R) and mounted on the coating head (100) downstream of said glaze veil (V), said ducts (50M,50V) being associated with the predetermined number of nozzles (40), with the expected transverse spacing.

6. Protective device according to claims 2 to 4, characterised in that the jet of compressed air, emitted by each of the aforementioned nozzles (40), has a conical shape, with a pre-established opening angle and with the median vertical plane of said emission cone (40C) substantially coplanar with the plane of the respective belt (20).

7. Protection device according to claims 2 to 4, characterised in that each of said nozzles (40) has, on a median vertical plane, an orientation of the axis of the emission cone (40C) of the air jet inclined with respect to the direction of advancement of said transport line (2), such that the ejected compressed air is directed substantially grazing the underlying belts (20).

8. Protection device according to any of claims 2 to 6, characterised in that said instantaneous opening / closing device (41), associated in the body of each nozzle (40), consists of an electromechanically operated needle valve, managed by said electronic control unit (7).

9. Protection device according to claim 1, characterised in that said dispensing means (4) comprise a plurality of calibrated holes, made in said at least one common supply duct (50) for the compressed air, the latter being mounted on the coating head (100) with a horizontal arrangement and substantially parallel to that of the aforementioned laminar veil (V) of glaze, and that the aforementioned calibrated holes are in a number equal to the aforementioned belts (20), with the expected transverse spacing.

10. Protection device according to claim 9, characterised in that said at least one duct (50) includes an upstream duct (50M), installed upstream of the aforementioned laminar veil (V) of glaze, and a downstream duct (50V), installed downstream of the same, calibrated holes provided in said ducts (50M,50V) being opposed to each other and aligned vertically with respect to the corresponding aforementioned belt (20).

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