ITRE20110073A1 - DEVICE FOR THE DISTRIBUTION OF INCIDENTAL SOLID MATERIAL - Google Patents

Description

DESCRIPTION

of the Italian Patent for Industrial Invention entitled:

`` DEVICE FOR THE DISPENSING OF INCOERENT SOLID MATERIAL ...

The present invention relates to a device for the controlled delivery of an incoherent solid material, for example in granular and / or powder form, as well as a method of operation of said device.

More specifically, the invention is aimed at a device for dispensing incoherent and possibly colored material on the surface of a product, for example in order to obtain a decorative effect on the latter.

Even more particularly, the invention is aimed at a device for dispensing the aforementioned material on the surface of a ceramic substrate, for example on a bed of incoherent ceramic powder, a partially compacted ceramic plate, a completely compacted, a dried ceramic plate or even a dried ceramic plate already partially decorated with liquid dyes.

In the ceramic field, some decoration techniques are currently known which allow to recreate a predetermined graphic effect, such as a pattern, a vein, a color spot or a shaded effect, by means of the controlled dispensing of colored materials on a ceramic substrate. in an incoherent solid state, including for example atomised mixtures, atomised glazes, grits, frits or the like.

This controlled dispensing can be performed with the aid of special devices, commonly called print heads, which include a hopper for containing the material to be dispensed, and a plurality of vibrating elements which are arranged side by side to define an accumulation plane. inclined which is able to receive the material coming out from a lower mouth of the containment hopper in support. This accumulation plane is normally positioned at a short distance below the outlet and is inclined at an angle lower than the angle of friction that the material generates on the accumulation plane itself. In this way, when the vibrating elements are inert, the accumulation surface is able to obstruct and stop the flow of material exiting the containment hopper. When a vibrating element vibrates, the material progressively slides on it until it falls from one of its edges, while new material coming out of the containment hopper accumulates on the vibrating element itself. More in particular, each vibrating element generally comprises a flexible lamella able to define a portion of the aforesaid accumulation plane, and a body of piezoelectric material fixed to said flexible lamella. Following an appropriate electric excitation signal, the piezoelectric material body enters into vibration, simultaneously setting the entire vibrating element into vibration, in such a way as to make a part of the material accumulated on the flexible lamella fall on the underlying ceramic substrate.

The electric excitation signal is sent to each body of piezoelectric material through a respective electric wire independently from the others, so that each vibrating element can be set in vibration and controlled individually, thus allowing a punctual management of the material supply. which allows a very precise distribution of the material itself on the surface of the ceramic substrate to be decorated.

The electrical excitation signals are managed by an appropriate computerized control unit, which is configured to regulate the flow rate of the material that falls from each vibrating element, and therefore the quantity delivered to each surface unit to be decorated, modulating the frequency and / or amplitude of the relative electrical excitation signal.

A drawback of this solution consists in the fact that the material deposited on the accumulation plane tends to adhere to the surface of the flexible lamellae, forming a sort of encrustation which is not removed even when the flexible lamella is vibrated. This phenomenon manifests itself more on the flexible lamellae that are less used in the work phase and is mainly caused by the humidity contained inside the material which, in contact with the cold surface of the lamella, tends to condense, wetting the material accumulated which compacts and increases its adhesiveness.

This phenomenon is unacceptable as the encrustation of material that remains adhered to the flexible blade reduces the outlet section of the containment hopper, and progressively alters the dynamic characteristics of the flexible blade itself. Consequently, with the same electrical characteristics of the excitation signal, a flexible lamella â € œincrustedâ € is not able to discharge the flow rate of material foreseen in the calibration phase, thus introducing supply errors that compromise or at least worsen the correct distribution of the material on the surface of the product to be decorated.

An object of the present invention is therefore to solve, or at least significantly mitigate, the aforementioned drawback of the known art. Another aim is to reach the aforementioned objective within the ambit of a simple, rational and low cost solution.

These and other objects are achieved thanks to the characteristics of the invention reported in the independent claims. The dependent claims outline preferred and / or particularly advantageous aspects of the invention.

In particular, an embodiment of the invention makes available a device for dispensing an incoherent solid material, comprising a plurality of vibrating elements arranged side by side to support said material, each of which is associated with a means piezoelectric suitable for converting an electric excitation signal into a mechanical vibration which can cause a fall of material from the vibrating element, and heating means for heating said vibrating elements.

Thanks to this solution it is advantageously possible to heat the vibrating elements so as to locally evaporate the humidity contained in the material, preventing the formation of unwanted encrustations.

According to an aspect of the invention, the heating means can comprise one or more heating elements, or elements individually adapted to emit a quantity of heat which is then transferred to the vibrating elements. Each of these heating elements can comprise, for example, an electric resistance or a radiating lamp.

This aspect of the invention has the advantage of making possible a series of particularly simple and reliable solutions for heating the vibrating elements.

One of these solutions provides that the heating means comprise a heating element configured to heat the entire plurality of vibrating elements alone. In this way the installation costs are advantageously reduced.

Another solution provides that the heating means comprise a plurality of heating elements, each of which is configured to heat a respective vibrating element. This improves the control and the efficiency of heating of each vibrating element.

According to an aspect of the invention, the heating means outlined above can be configured to heat the vibrating elements directly or indirectly, for example by heating a structure of thermally conductive material suitable to support the vibrating elements.

The first solution has the advantage of a better thermal efficiency, while the second solution has the advantage of being constructively simpler.

According to another and different aspect of the invention, the dispensing device can further comprise means for cleaning the vibrating elements.

In this way, if an undesired encrustation of material to be dispensed forms on the vibrating elements, these cleaning means can be activated, manually or automatically, so as to remove said encrustation.

The cleaning means can also be activated and used to remove the particles of material to be dispensed that may have slipped and wedged between two adjacent vibrating elements, in order to prevent the vibration of one of these vibrating elements from also being transmitted to the other, generating an unwanted or incorrect dispensing of the material.

According to an aspect of the invention, said cleaning means comprise at least one blowing device suitable for blowing a stream of air onto the vibrating elements.

This aspect of the invention has the advantage of providing a particularly simple solution for cleaning the vibrating elements from residues of material to be dispensed.

Means for heating the air stream can optionally be associated with said blowing device.

In this way, the vibrating elements are hit by a current of hot air which allows the encrusted or trapped material to be dried, reducing its compactness and adhesiveness and therefore facilitating its removal.

Said blowing device can also be associated with means for adding a dry powdered material to the air stream.

This dry powdered material has the advantage of increasing the mechanical cleaning action exerted by the air current on the vibrating elements.

According to another and different aspect of the invention, the vibrating elements can be provided with a coating of non-stick material, i.e. with a low coefficient of friction with respect to the material to be dispensed, such as compounds of FEP (Fluorinated ethylene propylene) or PTFE (Polytetrafluoroethylene).

Thanks to this solution, the smoothness of the vibrating elements is advantageously increased, reducing the possibility that the material to be dispensed adheres to them.

According to another and different aspect of the invention, each vibrating element is shaped in such a way as to have reduced thickness in correspondence with the lateral edges facing the adjacent vibrating elements.

This solution has the advantage of reducing the surface with which each vibrating element faces the adjacent ones, correspondingly reducing the risk that particles of material to be dispensed can get stuck between two adjacent vibrating elements, compromising their efficiency as explained above.

The invention also makes available a method of operation of a device for dispensing an incoherent solid material, the device comprising a plurality of vibrating elements arranged side by side to support said material, each of which is associated with a piezoelectric means suitable for converting an electrical excitation signal into a mechanical vibration which can cause a fall of material from the vibrating element, characterized by the fact that the operating method involves the phase of heating the vibrating elements.

This method achieves the aforementioned advantage in relation to the device, that is to locally evaporate the humidity contained in the material to be dispensed, preventing the formation of unwanted encrustations.

According to an aspect of the invention, said heating step provides for heating the vibrating elements to a temperature between 30 ° C and 50 ° C.

This solution has the advantage of achieving good result efficiency with low energy consumption.

According to another different aspect of the invention, the method involves the step of cleaning the vibrating elements.

This cleaning phase can be performed periodically or on command when necessary, and has the advantage of allowing the removal of any encrustations of material formed on the vibrating elements and / or particles of material that may be stuck between adjacent vibrating elements.

The cleaning phase is preferably performed when the vibrating elements are inactive, i.e. when the dispensing device is off, so as not to interfere with the correct dispensing of the material during production.

According to an aspect of the invention, said cleaning step involves blowing a current of air on the vibrating elements.

As previously explained, this aspect of the invention has the advantage of providing a particularly simple solution for cleaning the vibrating elements from residues of material to be dispensed.

According to another aspect of the invention, said air stream is hot, so as to be able to advantageously dry the encrusted or trapped material, reducing its compactness and adhesiveness and therefore facilitating its removal.

According to a further aspect of the invention, a dry powder material is added to said air stream, so as to advantageously increase the mechanical cleaning action exerted by the air stream on the vibrating elements.

Further characteristics and advantages of the invention will become evident by reading the following description provided by way of non-limiting example, with the aid of the figures illustrated in the attached tables.

Figure 1 is a schematic side view of an apparatus for the distribution of incoherent solid materials on a surface to be treated with said materials.

Figure 2 is a partial and enlarged perspective view of a detail of the device for the controlled delivery of an incoherent solid material, belonging to the apparatus of Figure 1. Figure 3 is Figure 2 referring to a first form of alternative embodiment of the heating means.

Figure 4 is Figure 2 referring to a second alternative embodiment of the heating means.

Figure 5 is Figure 2 referring to a third alternative embodiment of the heating means.

Figure 6 is the section VI-VI of Figure 2 on a further enlarged scale.

Figure 7 is Figure 6 referred to a first alternative embodiment of the vibrating elements.

Figure 8 is Figure 6 referred to a second alternative embodiment of the vibrating elements.

Figure 1 schematically illustrates an apparatus 300 for the controlled distribution of incoherent solid materials, for example in granular and / or powdery form, on surfaces to be treated with said materials. The apparatus 300 can be used in the ceramic field for the distribution of one or more incoherent and possibly colored materials on the surface of a ceramic substrate, for example in order to obtain a decorative effect on the latter. The ceramic substrate can be a bed of incoherent ceramic powder, a partially compacted ceramic plate, a fully compacted ceramic plate, a dried ceramic plate and also a dried ceramic plate already partially decorated with other liquid dyes. The incoherent solid materials distributed by the apparatus 300 can be atomized mixtures, atomized glazes, grits, frits or the like.

The apparatus 300 schematically comprises a support surface 400 for the ceramic substrate S to be treated, and at least one device 100 for dispensing in a controlled manner an inconsistent solid material P among those mentioned above, which is positioned above the support surface 400 , so that the material P dispensed by it can deposit on the underlying ceramic substrate S.

The apparatus 300 can be provided with suitable handling means which are generally adapted to allow relative and coordinated movements between the support surface 400 and the dispensing device 100 above, in order not only to distribute the material P over the entire substrate ceramic S but also to create pre-established designs or decorative motifs. In this regard, some embodiments provide that the support surface 400 is mobile, for example defined by a sliding conveyor belt, and that the dispensing device 100 is mounted on a fixed structure. Other embodiments, on the other hand, provide for the support surface 400 to be fixed, and for the dispensing device to be mounted on handling means, for example on a trolley device or an anthropomorphic robot, which allow it to move with respect to the support surface 400. fixed. Other embodiments can provide both a mobile support surface 400 and also means for moving the dispensing device 100.

The dispensing device 100 comprises a containment hopper 105, which is adapted to be filled with the material P to be dispensed. The containment hopper 105 develops mainly along a horizontal longitudinal axis A, with respect to which it has a constant cross section, substantially trapezoidal, which narrows downwards. The containment hopper 105 therefore has at the top a wide inlet 110, through which the material P is loaded inside, while on the bottom, it has a narrower outlet 115 with full longitudinal development, through which the material P escapes downwards by gravity. Some embodiments may provide that the outlet 115 is divided in plan into a succession of distinct passage ports (not shown) which follow one another in the direction of the longitudinal axis A. These passage ports can be defined by a succession of vertical separator baffles which are fixed to the containment hopper 105 under the outlet mouth 115.

The dispensing device 100 also comprises an accumulation plane, globally indicated with 200, which is integral with the containment hopper 105 and is positioned a short distance below the outlet 115. This distance can be included, for example, between 0, 2 and 1 cm. The accumulation plane 200 is oriented parallel to the longitudinal axis A of the containment hopper 105 and has such dimensions as to contain, in plan, the entire area of the outlet outlet 115. In this way, the accumulation plane 200 It is adapted to receive in support the material P which emerges from the outlet 115 until it completely stops its descent. In other words, the position and dimensions of the accumulation plane 200, with respect to the containment hopper 105, are such that it is normally able to accumulate a quantity of material P which obstructs the outlet mouth 115. The accumulation plane 200 it can be slightly inclined with respect to the vertical so that the accumulated material P tends to slide towards a fall edge 205 of the accumulation plane 200, which exceeds the outlet mouth 115. The angle of inclination of the accumulation plane 200 Ã It is in any case lower than the friction angle that the accumulated material P generates on the accumulation plane 200 itself, so as to guarantee the possibility of stopping the flow of material P exiting the outlet 115. The angle of inclination of the plane of accumulation 200 can be, for example, lower than 20 ° C.

More in detail, the accumulation plane 200 is defined by a plurality of distinct flexible lamellae 210, generally rectangular in shape, which are arranged coplanar and parallel to each other and in succession in the direction of the longitudinal axis A of the containment hopper 105 (see figure 2).

The flexible lamellas 210 are preferably made of thin metal sheet, for example of steel. The lateral distance between each flexible lamella 210 and the adjacent ones is sufficiently small to prevent the material P accumulated on the accumulation plane 200 from drawing. The flexible lamellae 210 are cantilevered to a common support structure 215. Said support structure 215 can comprise for example a clamp system suitable for gripping one end of each flexible lamella 210, leaving the opposite end free to oscillate vertically. In the example illustrated, said clamp system comprises two jaws, each of which is shaped like a flat bar that develops mainly in the direction of the longitudinal axis A, of which an upper jaw 216 and a lower jaw 217 including the flexible slats 210 are interposed. In quiet conditions, the free ends of all the flexible slats 210 are aligned with each other to define the falling edge 205 of the storage surface 200.

As illustrated in Figure 6, the flexible lamellas 210 can have a perfectly flat and squared shape. In other embodiments, the flexible lamellae 210 could be slightly concave, at least at their free end. This concavity could be facing upwards, so as to concentrate the material P in the center of each flexible lamella 210, or it could be facing downwards, so as to concentrate the material P along the sides of each flexible lamella 210, that is, between a flexible lamella 210 and the adjacent one.

A respective body of piezoelectric material 220 is fixed at the bottom to each flexible lamella 210. This body of piezoelectric material 220 can be shaped, for example, as a relatively thin plate which is glued under the respective flexible lamella 210. The resulting vibrating group 235 can be cantilever mounted on the support structure 215, for example clamped in a vice together with the flexible lamella 210 to which it is directly associated. A respective electric cable 225 is joined to each body of piezoelectric material 220. The electric cable 225 can be joined to the body of piezoelectric material 220 by means of a welding 230. Of course, the welding 230 may not be present and may possibly be replaced by a different one. type of electrical connection, for example from a rubbery contact. Through the respective electrical cable 225, each body of piezoelectric material 220 can receive electrical excitation signals, typically sinusoidal or square wave alternating current or voltage signals. In response to these electrical signals of excitation, the body of piezoelectric material 220 is adapted to perform corresponding mechanical vibrations, which are consequently transmitted also to the respective flexible lamella 210. In practice, the electrical signals of excitation which are applied to the body of piezoelectric material 220 induce a mechanical vibration of the entire vibrating group 235 which globally comprises the body of piezoelectric material 220 itself, any welding 230 which joins the body of piezoelectric material 220 to the electric cable 225, and the respective flexible blade 210.

Due to the vibration of the vibrating unit 235, the material P accumulated on the corresponding flexible lamella 210 progressively slides towards the falling edge 205 of the accumulation plane 200, from which it falls downwards by gravity, thus being discharged onto the surface of the ceramic substrate S below. As the material P falls from the falling edge 205, other material P emerges from the outlet 115 of the containment hopper 105 and accumulates on the flexible lamella 210, so that the flow of discharged material P is continuous and free. of interruptions. When the electrical excitation signal is interrupted, the vibrating unit 235 returns to a state of rest which interrupts the sliding of the material P on the flexible lamella 210, and therefore also its delivery.

In the embodiment shown in Figure 7, each flexible blade 210 has a coating 211 of non-stick material. Said coating 211 covers at least the upper surface of each flexible lamella 210, that is the one which helps to define the accumulation plane 200. However, it is not excluded that each flexible lamella 210 can be entirely covered with the coating 211 of non-stick material. With respect to the material P, the coating 211 of non-stick material generally has a lower friction coefficient than that of the flexible lamella 210, in such a way as to increase the smoothness of the accumulation plane 200 and therefore facilitate the discharge of the material P when the lamella flexible 210 is placed in vibration. More specifically, the 211 coating can be made with compounds of FEP (Fluorinated ethylene propylene) or PTFE (Polytetrafluoroethylene). The coating 211 is applied and made integral with the flexible lamellae 210 by means of operating techniques known per se. Naturally, the coating 211 of non-stick material can be applied to flexible blades 210 of any shape and size, and therefore also to flexible blades 210 of a different shape than those shown in figure 7.

In the embodiment shown in Figure 8, each flexible lamella 210 is shaped in such a way as to have reduced thickness at the lateral edges 212 that face the adjacent flexible lamellae 210, correspondingly reducing the surface of said lateral edges. In this way, the particles of material P that accidentally were to slip between two adjacent flexible lamellae 210 would find a faster evacuation downwards, advantageously reducing the risk that they could get stuck, compromising the correct functioning of the single flexible lamellae 210. Nellâ € In the example illustrated, this reduction in thickness is obtained by shaping the lateral edges 212 of each flexible lamella 210 so that they have a longitudinal flaring 213. Said flare 213 has a rounded section profile with the concavity facing outwards and downwards. In this way, each flexible lamella 210 has a cross section of a substantially trapezoidal shape, with the major base facing upwards to define the accumulation plane 200. Although it is not explicitly shown, also the flexible lamellae 210 conforming to this shape embodiments can be covered with the coating 211 of non-stick material as described above.

From the point of view of electrical actuation, the dispensing device 100 can be associated with a voltage generator 500, which is electrically connected with the body of piezoelectric material 220 of each vibrating group 235, through the respective electric cable 225. Said voltage generator 500 is configured to generate and apply the appropriate electrical excitation signals to each of said bodies of piezoelectric material 220, so as to be able to vibrate each vibrating group 235 of the dispensing device 100 independently from the others. Excitation signals are typically sinusoidal or square wave voltage signals.

The dispensing device 100 further comprises heating means adapted to heat the flexible lamellae 210 during operation, so as to locally evaporate the humidity contained in the material P accumulated thereon, mainly to prevent the formation of undesired encrustations. Preferably, the heating means are adapted to heat the flexible lamellae 210 to a temperature comprised between 30 ° C and 50 ° C. Said heating means can comprise one or more heating elements, that is elements able to generate and give off heat which is then transferred to the flexible lamellae 210. Each heating element can comprise any heat generation system, for example one or more electric resistances or a lamp. radiant, ie a lamp capable of emitting a light capable of heating objects by radiation. The heating elements can also be configured to heat the flexible lamellae 210 directly or indirectly.

In the embodiment illustrated in Figures 1 and 2, said heating means comprise for example a heating element 240 configured to heat by itself all the flexible lamellae 210 of the dispensing device 100. Said heating element 240 comprises one or more electrical resistances (not visible) , which are connected to a current generator 255 by means of a usual electrical connection 241. In this way, the current generator 255 is able to generate an electric current which passes through the electrical resistances, producing heat. Said electric resistances are enclosed in an external body 242 of the heating element 240, which is made of thermally conductive material. The external body 242 has the shape of a flat bar, which develops mainly in the direction of the longitudinal axis A of the hopper 105, and is placed in direct contact with all the flexible blades 210, interposed between the upper jaw 216 of the support structure 215 and the fixed ends of the flexible blades 210. In this way, the heat emanating from the external body 242 of the heating element 240 is transmitted directly to the flexible blades 210.

In the embodiment illustrated in Figure 3, the heating means comprise a heating element 240 entirely similar to that described above. Also in this case, the heating element is configured to heat by itself all the flexible lamellae 210 of the dispensing device 100, but indirectly. More specifically, the outer body 242 of the heating element 240 is not in direct contact with the flexible lamellae 210, but is applied in direct contact over the upper jaw 216 of the support structure 215. In this way, the heat emanating from the external body 242 of the heating element 240 is transmitted to the support structure 215 and from this, indirectly, to the flexible lamellae 210. Naturally, this embodiment provides that at least the upper jaw 216 of the support structure 215 is made of thermally conductive material.

In the embodiment illustrated in Figure 4, the heating means comprise a plurality of heating elements 245, each of which is adapted to heat a respective flexible blade 210. Each heating element 245 comprises at least one electrical resistance (not shown), which It is incorporated in an external body 246 of thermally conductive material. The electrical resistance of each heating element 245 is connected to the current generator 255 by means of a usual electrical connection (not shown), so that each heating element 245 can be powered independently from the others. In the example illustrated, the external body 246 has the shape of a block, which is placed in direct contact with a respective flexible lamella 210, interposed between the upper jaw 216 of the support structure 215 and the fixed end of the flexible lamella 210 itself. The external body 246 of each heating element 245 is further spaced from the external body 246 of all the other heating elements 245. In this way, the heat emanating from the external body 246 of each of the heating element 245 is transmitted substantially only to the respective flexible lamella 210.

In the embodiment of Figure 5, the heating means instead comprise an irradiating lamp 250, which is positioned so as to generate a beam of light which strikes all the flexible blades 210 of the dispensing device 100. Said irradiating lamp 250 is powered from the current generator 255, to which it is connected by means of the usual electrical connections (not shown). Alternatively, the heating means could comprise a plurality of these radiating lamps 250, each capable of generating a beam of light which strikes a respective group of flexible blades 210.

From the above, it is however evident that a person skilled in the art could design the heating means in many other different ways, without taking any further inventive step with respect to what has been described above, and therefore without departing from the general concept underlying the proposed solution.

Finally, the dispensing device 100 comprises means for cleaning the flexible blades 210, which can be activated, manually or automatically, periodically or only on command, for example to remove particles of material P which are encrusted on the flexible blades 210 and / or which are wedged in the gaps between adjacent flexible slats 210. In the example illustrated, said cleaning means comprise one or more blowing devices 260 (per se known), which are individually adapted to generate and blow a high-speed current of air onto the flexible blades 210, so that encrusted and / or trapped material P to be removed mechanically. Each blower device 260 can comprise for example a conveying duct 261 adapted to connect a delivery nozzle 262 with a reservoir 263 containing compressed air, and a valve 264, preferably electrically operated, which is placed along the conveying duct 261 , to selectively prevent or allow air to escape. Means can be associated with the blowing device 260 to heat the air stream that is blown onto the flexible lamellae 210, so as to be able to dry the encrusted and / or trapped material, reducing its compactness and adhesiveness and thus facilitating its removal. . Said heating means can comprise for example one or more heating elements 265, of the type described above, which can be applied to the tank 263. Each blowing device 260 can also be associated with means for adding a dry powder material to the stream. of air which is blown onto the flexible slats 210, in order to increase the mechanical cleaning action exerted by the air current. Dry powdered material can be sand, for example. The means for adding this dry material to the air stream can comprise a containment hopper 270 for said dry powder material and a duct 271 adapted to connect said hopper 270 with the conveying duct 261. In this way, when the valve 264 is open, the air flowing in the conveying duct 261 drags the dry powder material with it towards the dispensing nozzle 262, from which they come out substantially mixed. The dry powder material that is removed from the air stream is constantly replaced by new dry powder material which descends from the hopper 270 through the duct 271.

An electronic control unit 600 can be connected to the dispensing device 100, which is configured to generate and send to the voltage generator 500 control signals suitable for activating, interrupting and regulating the electrical excitation signals applied to each body of piezoelectric material. 220 of the dispensing device 100. The electronic control unit 600 can also be configured to generate and send command signals to the means suitable for creating the relative movement between the support surface 400 and the dispensing device 100, so as to coordinate them in based on the distribution of material P to be obtained on the ceramic substrate S.

The electronic control unit 600 is also configured to generate and send to the current generator 255 control signals suitable for activating, interrupting and regulating the electrical supply of the heating elements of the flexible slats 210, i.e. the heating elements indicated with 240, 245 or 250 depending on the embodiment considered. During the operational operation of the dispensing device 100, i.e. when the dispensing device 100 is used productively to distribute the loose material P on a ceramic substrate S, the electronic control unit 600 can maintain the heating elements 240, 245 or 250 always active, or it can activate the heating elements 240, 245 or 250 only for a limited time interval, and possibly repeated periodically. In the case of the embodiment of Figure 4, the electronic control unit 600 could also selectively activate only one or more of the heating elements 245, for example to heat only the flexible lamellae 210 which are less used for discharging the material P. The electronic control unit 600 is also connected to the valve 264 of each blower device 260, and is configured to generate and send command signals able to selectively open and close said valve 264, so as to allow or not the blowing of the current of air, preferably hot and containing dry powdered material, towards the flexible blades 210 to clean them. In particular, the electronic control unit 600 can activate the blowing of the air current automatically or by manual command. In both cases, the electronic control unit 600 is configured to activate blowing only when the dispensing device 100 is inactive, i.e. when it is not used to distribute the incoherent material P on a ceramic substrate S.

To perform these functions, the electronic control unit 600 can comprise a computerized processing unit (CPU) in communication with a storage unit 605 and an interface bus that can be configured to transmit to the voltage generator 500, and to the various handling means, the command signals generated by the CPU. The 605 storage unit can include various types of data storage systems, including optical, magnetic, solid and other non-volatile memories. The CPU is configured to execute instructions contained in one or more control programs (software) stored in the storage unit 605. In particular, these control programs are written to implement all the calibration, control and management methods that will be described below, allowing the CPU to perform all the steps of said methods.

In conclusion, it should be noted that the apparatus 300 could comprise a plurality of dispensing devices 100 of the type described above, each of which can be arranged to dispense a different material P, for example having a different coloring, to create more complex decorations. . The dispensing devices 100 of said plurality can be arranged side by side, or with the longitudinal axes A of the respective containment hoppers 105 aligned with each other, or one after the other in an orthogonal direction with respect to the longitudinal axes A, possibly slightly offset with each other, to obtain interlocking graphics of various types of powders. Also in this case, the plurality of dispensing devices 100 can be fixedly mounted with respect to a mobile support surface 400, or can be mounted on handling means adapted to move it with respect to a fixed support surface 400, or both. Obviously, a person skilled in the art can make numerous modifications of a technical-applicative nature to the apparatus 300 and the dispensing device 100, without thereby departing from the scope of the invention as claimed below.

REFERENCES

100 dispensing device

105 containment hopper

110 inlet

115 outlet

200 accumulation plan

205 falling edge

210 flexible blade

211 lining

212 lateral border

213 flaring

215 support structure

216 upper jaw

217 lower jaw

220 body of piezoelectric material

225 electric cable

230 welding

235 vibrating group

240 heating element

241 electrical connection

242 outer body of the heating element 245 heating element

246 external body of the heating element 250 radiating lamp

255 current generator

260 blower device

261 conveying duct 262 dispensing nozzle

263 tank

264 valve

265 heating element

270 hopper

271 duct

300 apparatus

400 support surface

500 voltage generator

600 electronic control unit 605 storage unit

Longitudinal axis hopper S ceramic substrate

P material

Claims (17)

CLAIMS 1. A device (100) for dispensing an incoherent solid material (P), comprising a plurality of vibrating elements (210) arranged side by side to support said material (P), each of which is associated with a piezoelectric means (220) suitable for converting an electric excitation signal into a mechanical vibration that can cause a fall of material (P) from the vibrating element (210), characterized in that it comprises heating means (240, 245, 250) to heat said vibrating elements (210). A device (100) according to claim 1, characterized in that said heating means comprise at least one heating element (240, 245, 250) adapted to give off heat. A device (100) according to claim 2, characterized in that said heating element (240) is configured to heat the entire plurality of vibrating elements (210). A device (100) according to claim 2, characterized in that said heating means comprise a plurality of said heating elements (245), each of which is configured to heat a respective vibrating element (210). 5. A device (100) according to any one of the preceding claims, characterized in that said heating means (240) are configured to heat a structure (215) of thermally conductive material able to support said plurality of vibrating elements (210). A device (100) according to any one of the preceding claims, characterized in that it comprises means (260) for cleaning the vibrating elements (210). 7. A device (100) according to claim 6, characterized in that said cleaning means comprise at least one blowing device (260) able to blow a current of air on the vibrating elements (210). 8. A device (100) according to claim 7, characterized in that means (265) for heating the air stream are associated with said blower device (260). 9. A device (100) according to any one of claims 7 to 8, characterized in that said blower device (260) is associated with means (270, 271) for adding a dry powder material to the air stream . A device (100) according to any one of the preceding claims, characterized in that the vibrating elements (210) are provided with a coating (211) of non-stick material. 11. A device (100) according to any one of the preceding claims, characterized in that each vibrating element (210) is shaped in such a way as to have reduced thickness at the lateral edges (212) facing the vibrating elements (210) adjacent. 12. A method of operation of a device (100) for dispensing an incoherent solid material (P), the device (100) comprising a plurality of vibrating elements (210) arranged side by side to support said material (P ), each of which is associated with a piezoelectric medium (220) capable of converting an electric excitation signal into a mechanical vibration that can cause a fall of material (P) from the vibrating element (210), characterized by the fact that the method of operation involves the step of heating the vibrating elements (210). 13. A method according to claim 12, characterized in that said heating step provides for heating the vibrating elements (210) to a temperature between 30 ° C and 50 ° C. A method according to any one of claims 12 to 13, characterized in that it provides for the step of cleaning the vibrating elements (210). 15. A method according to any one of claims 14, characterized in that said cleaning step involves blowing a stream of air on the vibrating elements (210). 16. A method according to claim 15, characterized in that said stream of air is hot. 17. A method according to any one of claims 15 to 16, characterized in that a dry powdered material is added to said air stream.