WO2013045989A1

WO2013045989A1 - Device and method for dispensing loose solid material

Info

Publication number: WO2013045989A1
Application number: PCT/IB2012/001787
Authority: WO
Inventors: Gildo Bosi; Silvano Valli; Stefano Scardovi
Original assignee: Sacmi - Cooperativa Meccanici Imola Societa' Cooperativa
Priority date: 2011-09-26
Filing date: 2012-09-13
Publication date: 2013-04-04
Also published as: BR112014007106A2; BR112014007106B1; ITRE20110073A1; EP2760594A1; EP2760594B1; PL2760594T3; MX2014003457A; ES2555107T3; RU2014110725A; PT2760594E; MX352544B; CN103958073B; CN103958073A; RU2595708C9; RU2595708C2

Abstract

A device (100) for dispensing a loose solid material (P), comprising a plurality of vibrating elements (210) arranged flanked to one another such as to restingly support the material (P), each of which is associated to a piezoelectric means (220) suitable for converting an electrical excitation signal into a mechanical vibration which can cause a fall of material (P) from the vibrating elements (210), and heating means (240, 245) for heating the vibrating elements (210).

Description

DEVICE AND METHOD FOR DISPENSING LOOSE SOLID MATERIAL

TECHNICAL FIELD

The present invention relates to a device for controlled dispensing of a loose solid material, for example in granular and/or powder form, as well as a functioning method of the device.

In more detail, the invention relates to a device for dispensing loose and possibly coloured material onto a surface of a product, for example with the aim of obtaining thereon a decorative effect.

Still more in detail, the invention relates to a device for dispensing the material on a surface of a ceramic substrate, for example a bed of loose ceramic powder, a partially-compacted ceramic slab, a completely compacted ceramic slab, a dried ceramic slab or also a dried ceramic slab which is already partially-decorated with liquid colorants.

BACKGROUND ART

In the ceramic field, some decorating techniques are already known that enable recreating a predetermined graphic effect, such as for example a design, a veining pattern, a splash of colour or a nuanced effect, by means of controlled dispensing of a ceramic substrate of coloured material in the loose solid state, among which for example atomised mixtures, atomised glazes, grits, frits or the like.

This controlled dispensing can be performed with the aid of special devices, commonly known as printing heads, which comprise a containing hopper of the material to be dispensed, and a plurality of vibrating elements which are arranged reciprocally flanked such as to define an inclined accumulation plate which is suitable for restingly receiving the material exiting from a lower mouth of the containing hopper. This accumulation plane is normally positioned at a brief distance below the outlet mouth and is inclined by a smaller angle than a friction angle which the material generates on the accumulation plane. In this way, when the vibrating elements are inert, the accumulation plane is able to obstruct and halt the flow of material exiting from the containing hopper. When a vibrating element enters into vibration, the material progressively slides thereon up to falling from an edge thereof, while new material exiting from the containing hopper accumulates on the vibrating element.

In more detail, each vibrating element generally comprises a flexible blade suitable for defining a portion of the accumulation plane. Following an appropriate electric excitation signal, the body of piezoelectric material enters into a vibrating mode, at the same time setting the whole vibrating element in vibration, such as to cause a part of the accumulated material on the flexible blade to fall onto the underlying ceramic substrate.

The electric excitation signal is sent to each piezoelectric material body through a respective electric wire independently of the others, so that each vibrating element can be set in vibration and controlled individually, thus enabling a prompt management of the dispensing of the material, enabling a very precise distribution of the material on the surface of the underlying substrate to be decorated.

The electric excitation signals are managed by an appropriate computerised control unit, which is configured such as to regulate the flow rate of material which falls from each vibrating element, and thus the quantity dispensed on each surface unit to be decorated, modulating the frequency and/or the amplitude of the relative electric excitation signal.

The solution above is disclosed in the document WO 2009/1 861 1 A1 in the name of the applicant.

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 blades, forming a sort of encrustation which does not get removed even when the flexible blade is set in vibration. This phenomenon is more greatly manifested on the flexible blades that are least used during the working step and is mainly caused by the moisture contained internally of the material which, in contact with the cold surface of the blade, tends to condense, wetting the accumulated material that compacts and increases its degree of adhesion. This phenomenon is unacceptable as the encrustation of material remaining in adherence to the flexible blade reduces the outlet section of the containing hopper, and progressively alters the dynamic characteristics of the flexible blade. Consequently, given same electrical characteristics of the excitation signal, an "encrusted" flexible blade is not able to unload the amount of material set during the calibrating step, thus introducing errors in dispensing which compromise or at least have a negative effect on the correct distribution of the material on the surface of the product to be decorated. Other different methods and means are kown to achieve a regular distribution of a powdered material on a surface.

The document US 2004/0101619 A1 discloses a method in which the powder particles are incorporated in an array of droplets of a liquid controlled by computer means.

The document FR 1 575 436 A, discloses an apparatus for handling powder material and creating a flow of material which falls through a bundle of parallel distanced rigid wires, horizontal and orthogonal on a receiving surface.

The bundle is subjected to vibrations, and the material can be conveniently electrostatically charged and or warmed, to regularise the distribution of the powder.

The structure comprising the bundle can be warmed to avoid adhesion of the powder thereto.

The warming of the whole structure is not suitable in the ceramic field, where maintaining a desired humidity of the powder is essential.

The warming of the whole structure, of a large part thereof, will result in an irregular humidity modification of the powder mass which can negatively affect the following steps of the ceramic process.

Nothing is said by the prior art about regulating the flow rate of material which falls from the vibrating element.

DISCLOSURE OF THE INVENTION

An aim of the present invention is therefore to obviate, or at least significantly mitigate, the above-cited drawback in the prior art. A further aim is to attain the above objective with a solution that is simple, rational and relatively inexpensive. These and other aims are attained with the characteristics of the invention as reported in the independent claims. The dependent claims delineate preferred and/or especially advantageous aspects of the invention.

In particular, in an embodiment of the invention a device is disclosed for dispensing a loose solid material, comprising a plurality of vibrating elements arranged flanked such as to restingly support the material, each of which is associated to a piezoelectric means destined for convert an electrical excitation signal into a mechanic vibration that can cause a fall of material from the vibrating element, and heating means for heating the vibrating elements.

With this solution, it is advantageously possible to heat the vibrating elements such as to cause local evaporation of the moisture contained in the material, thus preventing formation of undesired encrustation.

The heating means act only on the substrate of material which contact the vibrating elements, and undesired modification of the humidity of the material mass is avoided, so that the material can maintain his convenient and desired humidity suitable for the following steps.

In an aspect of the invention, the heating means can comprise one or more heating elements, i.e. elements singly suitable for emanating a quantity of heat which is then transferred to the vibrating elements. Each of the heating elements can comprise for example an electrical resistance.

This aspect of the invention has the advantage of providing a series of solutions that are particularly simple and reliable for heating the vibrating elements.

In one of the solutions the heating means comprise a heating element configured such as alone to heat the whole plurality of vibrating elements. In this way, plant costs are advantageously reduced.

in a further solution, the heating means comprise a plurality of heating elements, each of which is configured such as to heat a respective vibrating element. In this way the control and effectiveness of the heating of each vibrating element is improved. In an aspect of the invention, the above-delineated heating means can be configured such as to heat the vibrating elements directly or indirectly, for example by heating a structure of heat-conductive material suitable for supporting the vibrating elements.

The first solution has the advantage of greater heat efficiency, while the second solution has the advantage of being constructionally simpler.

In a further and different aspect of the invention, the dispensing device can further comprise means for cleaning the vibrating element.

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, such as to remove the encrustation.

The cleaning means can also be activated and used to remove the particles of material to be dispensed which might have inserted and got trapped between two adjacent vibrating elements, such as to prevent the vibration of one of these vibrating elements from transmitting to another element, generating an undesired or wrong dispensing of the material.

In an aspect of the invention, the cleaning means comprise at least a blower device suitable for blowing an air current onto the vibrating elements.

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

In a further and different aspect of the invention, the vibrating elements can be provided with a non-stick coating, i.e. having a low coefficient of friction with respect to the material to be dispensed, such as, for example, FEP compounds (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 will adhere thereto.

In a further and different aspect of the invention, each vibrating element is conformed such as to present a reduced thickness at lateral edges thereof facingthe adjacent vibrating elements. This solution has the advantage of reducing the surface with which each vibrating element which faces the adjacent ones, correspondingly reducing the risk that particles of material to be delivered might get trapped between two adjacent vibrating elements and compromise the efficiency thereof, as explained above.

This invention further discloses a functioning method for dispensing a loose solid material, the device comprising a plurality of vibrating elements arranged flanked such as to restingly support the material, each of which is associated with piezoelectric means suitable for converting an electrical excitation signal into a mechanical vibration which can cause a fall of material from the vibrating element, characterised in that the functioning method comprises a step of heating the vibrating elements.

This method provides the above-mentioned advantage in relation to the device, i.e. to cause local evaporation of the moisture contained in the material to be dispensed, thus preventing formation of unwanted encrustations.

In an aspect of the invention, the heating step involves the vibrating elements to a temperature of between 30°C and 50°C.

This solution has the advantage of achieving a good results in terms of efficiency with moderate energy consumption.

In a further and different aspect of the invention, the method includes the step of cleaning the vibrating elements.

This step of cleaning can be performed periodically or on command when necessary, and has the advantage of enabling the removal of any encrustation deposits formed on the vibrating elements of material and/or the particles of material that may be trapped between adjacent vibrating elements.

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

In an aspect of the invention, the step of cleaning involves blowing a stream of air onto the vibrating elements. As stated above, this aspect of the invention has the advantage of providing a particularly simple solution for cleaning residues of the material to be dispensed from the vibrating elements.

In a further aspect of the invention, a dry powder material can be added to the air current, such as to advantageously increase the mechanical cleaning action of the air current on the vibrating elements.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will emerge from a reading the following description, given by way of non-limiting example, with the aid of the figures illustrated in the accompanying tables of drawings.

Figure 1 is a schematic lateral view of an apparatus for distributing loose solid materials onto a surface to be treated therewith.

Figure 2 is a partial and enlarged perspective view of a detail of the device for the controlled dispensing of a loose solid material, belonging to the apparatus of figure 1.

Figure 3 is figure 2 relating to a first alternative embodiment of alternative heater means.

Figure 4 is figure 2 relating to a second alternative embodiment of the alternative heater means.

Figure 6 is section VI-VI of figure 2, in further enlarged scale.

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

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

BEST MODE FOR CARRYING OUT THE INVENTION

Figure 1 schematically illustrates a blower device, for example an apparatus 300 for controlled distribution of loose solid materials, for example in granular and/or powder form on surfaces to be treated with such materials. The apparatus 300 can be used in the ceramic field for distribution of one or more loose and possibly coloured materials onto a surface of a ceramic substrate, for example with the aim of obtaining a decorative effect thereof. The ceramic substrate can be a bed of loose ceramic powder, a partially compacted ceramic slab, a dried ceramic slab and also a dried ceramic slab already partially decorated with other colorant liquids. The loose solid materials distributed by the apparatus 300 can be atomised mixtures, atomised glaze, grits, fried or the like.

The apparatus 300 schematically comprises a support plane 400 for the ceramic substrate S to be treated, and at least a device 100 for dispensing a loose solid material among the above-mentioned materials in a controlled manner P. The device 100 is positioned above the support plane 400, such that the material P dispensed therefrom can be deposited on the underlying ceramic substrate S.

The apparatus 300 can be equipped with suitable movement means that are, in general terms, suitable for enabling relative and coordinated movements between the support plane 400 and the overlying dispensing device 100, such as not only to distribute the material P over all the ceramic substrate of S but also to carry out designs or decorative motifs. In this regard, in some embodiments the support plane 400 is mobile, for example, defined by a slidable conveyor belt, and the dispensing device 100 is mounted on a fixed structure. In other embodiments the support plane 400 is fixed and the dispensing device is mounted on movement means, for example a carriage device or an anthropomorphic robot, which enable the movement means to move with respect to the fixed support plane 400. In other embodiments, both a mobile support plane 400 and movement means of the dispensing device 100 can be provided.

The dispensing device 100 comprises a containing hopper 105, which is suitable for being filled with the material P to be dispensed. The containing hopper 105 develops mainly according to a horizontal longitudinal axis A, with respect to which it exhibits a uniform section, substantially trapezoid, which tapers in a downwards direction. The containing hopper 105 exhibits a wide inlet mouth 1 10 at the top thereof, through which the material P is loaded internally thereof, while at the bottom thereof it exhibits a narrower outlet 1 5 developing over the whole longitudinal development, through which the material P exits in a downwards direction by force of gravity. In some embodiments the outlet mouth 1 15 can be subdivided in plan view into a succession of distinct passage mouths (not illustrated) that follow one another in the direction of the longitudinal axis A. The passage mouths can be defined by a succession of vertical separator walls which are fixed to the containing hopper 105 below the outlet mouth 1 15.

The dispensing device 100 further comprises an accumulating plane, denoted in its entirety by 200, which is solidly constrained to the containing hopper 105 and is positioned a short distance below the outlet mouth 1 15. This distance can be comprised for example between 0.2 and 1 cm. The accumulating plane 200 is orientated parallel to the longitudinal axis A of the containing hopper 105 and exhibits dimensions that are such as to contain, in plan view, the whole area of the outlet mouth 115. In this way, the accumulating plane 200 is suitable for restingly receiving the material P which exits from the outlet mouth 1 15 up to entirely halting the descent thereof. In other words, the position and dimensions of the accumulating plane 200, with respect to the containing hopper 105, are such that it is normally destined to accumulate a quantity of material P which obstructs the outlet mouth 1 15. The accumulating plane 200 can be slightly inclined with respect to the vertical such that the accumulated material P tends to slide towards a falling edge 205 of the accumulating plane 200, which advances past the outlet mouth 1 15. The angle of inclination of the accumulating plane 200 is however smaller than the friction angle that the accumulated material P generates on the accumulating plane 200 itself, such as to guarantee the possibility of halting the flow of material P exiting from the outlet mouth 15. The angle of inclination of the accumulating plane 200 can be for example less than 20°C.

In more detail, the accumulating plane 200 is defined by a plurality of distinct flexible blades 210, generally rectangular in shape, which are arranged coplanar, parallel and flanked to one another in succession in the direction of the longitudinal axis A of the containing hoper 105 (see figure 2). The flexible blades 210 are preferably made of a slim metal blade, for example steel. The lateral distance between each flexible blade 210 and the adjacent blades is sufficiently small to prevent the accumulated material P on the accumulating plane 200 from getting trapped between the blades. The flexible blades 210 are projecting fixed to a common support structure 215. The support structure 215 can comprise, for example, a clamping system suitable for clamping an end of each flexible blade 210, leaving the other end free to oscillate in a vertical direction. In the illustrated example, the clamp system comprises two jaws, each of which is conformed as a flat bar prevalently developing in the direction of the longitudinal axis A, i.e. an upper jaw 216 and a lower jaw 217, interposed between which the flexible blades 210 are clamped. In rest conditions, the free ends of all the flexible blades 210 are aligned to one another such as to define the falling edge 205 of the accumulating plane 200.

As shown in figure 6, the flexible blades 210 can exhibit a perfectly flat and square form. In other embodiments, the flexible blades 210 may be slightly concave, at least at the free ends thereof. The concavity might be facing upwards, such as to concentrate the material P at the centre of each flexible blade 210, or it could be facing downwards, such as to concentrate the material P along the flanks of each flexible blade 210, or between a flexible blade 210 and an adjacent one.

A respective body made of piezoelectric material 220 is inferiorly fixed to each flexible blade 210. The body of piezoelectric material 220 can be conformed for example as a relatively slim plate which is glued below the respective flexible blade 210. The resulting vibrating group 235 can be mounted projectingly on the support structure 215, for example clamped together with the flexible blade 210 to which it is directly associated. A respective electric cable 225 is joined to each body of piezoelectric material. The electric cable 225 can be joined to the body of piezoelectric material 220 by a weld seam 230. Naturally, the weld seam 230 may not be present and can possibly be replaced by a different type of electrical connection, for example a rubber contact. By means of the respective electrical cable 225 each body of piezoelectric material 220 can receive electrical excitation signals, typically alternating current signals or voltage sinusoid or square waves. In response to the electrical excitation signals, the body of piezoelectric material 220 is destined to perform corresponding mechanical vibrations, which consequently are transmitted also the a respective flexible blade 210. In practice, the electrical excitation signals that are applied to the body of piezoelectric material 220 induce a mechanical vibration of the whole vibrating group 235 which overall comprises the body of piezoelectric material 220 itself, the weld seam 230, if present, which joins the body of piezoelectric material 220 to the electric cable 225, and the respective flexible blade 210.

Owing to the vibration of the vibrating group 235, the material accumulated on the corresponding flexible blade 210 progressively slides towards the falling edge 205 of the accumulating plane 200, from which it falls by force of gravity in a downwards direction, thus being unloaded onto the surface of the underlying ceramic substrate S. As the material P falls from the edge of falling edge 205, other material P exits from the outlet 1 15 of the hopper 1 15 so as the flow of material P unloaded is continuous and without interruptions. When the electrical excitation signal is interrupted, the vibrating group 235 returns to a state of rest that halts the sliding of the material P on the flexible blade 210, and therefore dispensing thereof.

In the embodiment shown in figure 7, each flexible blade 210 exhibits a coating of non-stick material 21 1. The coating covers at least the upper surface 21 1 of each flexible blade 210, i.e. the surface that is part of the definition of the accumulating plane 200. However, each flexible blade 210 can be completely coated with non-stick coating material 21 1. In comparison with the material P, the non-stick coating material 21 1 generally has a lower friction coefficient than that of the flexible blades 210, so as to increase the smoothness of the accumulating plane 200, and thus facilitate the unloading of the material P when the flexible blade 210 is set in vibration. More specifically, the coating 21 1 can be realised with compounds of FEP (fluorinated ethylene propylene) or PTFE (polytetrafluoroethylene). The coating 21 1 is applied and made solid with the flexible blades 210 through operational techniques which are known. Naturally, the non-stick coating material 21 1 can be applied to flexible blades 210 of any shape and size, and therefore also to flexible blades 210 of different shape than the ones illustrated in figure 7.

In the embodiment shown in figure 8, each flexible blade 210 is shaped such as to exhibit a reduced thickness at the lateral edges 212 which face the adjacent flexible blades 210, correspondingly reducing the surface of the lateral edges. In this way, the particles of material P that might accidentally become lodged between two adjacent flexible blades 210 would be more rapidly evacuated downwards, advantageously reducing the risk that they might get jammed and thus compromise the proper functioning of the individual flexible blades 210. In the illustrated example, this reduction in thickness is obtained by shaping the lateral edges 212 of each flexible blade 210 such that they present a longitudinally-developing countersinking 213. The countersinking 213 exhibits a rounded section profile with the concavity facing externally and downwards. In this way, each flexible blade 210 has a substantially trapezoidal section, with the larger base facing upwards so as to define the accumulating plane 200. Though not explicitly represented, the flexible blades 210 of the embodiment can also be coated with nonstick coating material 2 1 as described above.

From the point of view of electrical actuation, the dispenser device 100 can be associated with a tension generator 500, which is electrically connected with the body of piezoelectric material 220 of each vibrating unit 235, through its electrical cable 225. The tension generator 500 is configured such as to generate and apply the appropriate electrical excitation signals to each of the bodies of piezoelectric material 220, such that each vibrating group 235 of the dispenser device 100 can be set in vibration independently of the others. The excitation signals are typically sinusoid or square wave tension signals. The dispening device 100 further comprises heating means for heating the flexible blades 210 during functioning, such as to cause local evaporation of the moisture contained in the material P accumulated thereon, mainly such as to prevent formation of undesired encrustations. The heating means are preferably capable of heating the flexible blades 210 to a temperature of between 30°C and 50°C. The heating means may comprise one or more heater elements, i.e. elements suitable for generating and emanating heat that is then transferred to the flexible blades 210.

In the embodiment illustrated in figures 1 and 2, the heating means comprise for example a heating element 240 configured such as by itself to heat all the flexible blades 210 of the dispensing device 100. The heating element 240 comprises one or more heating resistance elements (not visible), which are connected to a current generator 255 by means of an electrical connection 241 . In this way, the current generator 255 is capable of generating an electric current that passes through the heating elements, producing heat. The heating resistance elements are enclosed in an external body 242 of the heating element 240, which is made of a heat-conductive material. The external body 242 is shaped as a flat bar, which prevalently develops in the direction of the longitudinal axis A of the hopper 105, and is set 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 that emanates 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 the one described above. In this case too, the heating element is configured such as by itself to heat the flexible blades 210 of the dispenser device 100, but indirectly. More specifically, the external body 242 of the heating element 240 is not in direct contact with the flexible blades 210, but is applied in direct contact on the upper jaw 216 of the support structure 215. In this way, the heat from the outer body 242 of the heating element 240 is transmitted to the support structure 215 and from there indirectly to the flexible blades 210. Naturally, in this embodiment at least the upper jaw 216 of the support structure 215 is made of heat- conductive material.

In the embodiment illustrated in figure 4, the heating means comprise a plurality of heating elements 245, each of which is capable of heating a respective flexible blade 2 0. Each heating element 245 comprises at least a heating resistance element (not shown), which is incorporated in an external heat-conductive material. The electrical resistance of each heating element

245 is connected to the current generator 255 through a usual electrical connection (not shown), such that each heating element 245 can be powered independently of the others. In the illustrated example, the external body 246 is shaped as a block, which is placed in direct contact with a respective flexible blade 210, interposed between the upper jaw 216 of the support structure 215 and the fixed end of the flexible blade 210. The external body

246 of each heating element 245 is also distanced from the external body 246 of all the other heating elements 245. In this way, the heat emanated from the external body 246 of each heating element 245 is transmitted substantially only to the respective flexible blade 2 0.

From the above, it is clear that a technical expert in the field might design the heating means in many other and different ways, without making any further inventive step with respect to the above, and therefore without forsaking the general concept underpinning the proposed solution.

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, in order to remove particles of material P that are encrusted on the flexible blades 210 and/or which have become trapped in the spaces between adjacent flexible blades 210. In the illustrated example, the cleaning means comprise devices including one or more blowers 260 (of known type), which are individually capable of generating and blowing an air stream at high speeds onto the flexible blades 210, such as to mechanically remove encrusted and/or trapped material P. Each blower device 260 can include, for example, a conveyor conduit 261 suitable for connecting a dispensing nozzle 262, with a tank 263 containing compressed air, and a valve 264, preferably electrically commanded, which is located along the conveyor conduit 261 , for selectively preventing or enabling outlet of the air. Each blower device 260 can also be associated to means for adding a dry powder material to the air current which is blown onto the flexible blades 210, such as to increase the mechanical cleaning action performed by the air stream. The dry powder may be, for example a sand. The means for adding the dry material to the air current can comprise a containing hopper 270 for the dry powder material and a conduit 271 suitable for connecting the hopper 270 to the conveyor conduit 261 . In this way, when the valve 264 is open, the air that flows in the conveyor conduit 261 draws the dry powder material with it towards the dispensing nozzle 262, from which they exit substantially mixed. The dry powder material that is distanced by the air stream is constantly replaced by new dry powder material falling from the hopper 270 through the conduit 271 .

An electronic control unit 600 can be connected to the dispensing device 100, which is configured such as to generate and sent command signals to the tension generator 600, which command signals are 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 further be configured such as to generate and sent command signals to the means suitable for creating relative movement between the support plane 400 and the dispensing device 100, such as to coordinate them on the basis of the distribution of material P which is to be obtained on the ceramic substrate S.

The electronic control unit 600 is further configured such as to generate and send command signals to the current generator 255, which command signals are suitable for activating, interrupting and regulating the electrical supply of the heating elements of the flexible blades 210, i.e. the heating elements denoted by 240, 245 according to the considered embodiment. During operative functioning of the dispensing device 100, i.e. when the dispensing device 100 is used productively for distributing the loose material P on a ceramic substrate S, the electronic control unit 600 can maintain the heating elements 240, 245 constantly active, or it can activate the heating elements 240, 245 only for a limited time interval, which may be repeated periodically. In the case of the embodiment of figure 4, the electronic control unit 600 may also selectively activate only one or more of the heating elements 245, for example to heat only the flexible blades 210 which are less used for unloading the material P.

The electronic control unit 600 is also connected to the valve device 264 of each blower device 260, and is configured such as to generate and send command signals capable of selectively opening and closing the valve 264, in order to enable (or not) the blowing of the air current, preferably hot and containing dry powder, towards the flexible blades 210 in order to clean them. In particular, the electronic control unit 600 can activate the blowing of the air current automatically or manually on command. In both cases, the electronic control unit 600 is configured to activate the blowing only when the dispensing device 100 is idle, i.e. when it is not being used to distribute the loose material P onto a ceramic substrate S.

In order to carry out these functions, the electronic control unit 600 may comprise a computer processing unit (CPU) in communication with a memorising unit 605 and an interface bus that can be configured to transmit control signals generated by the CPU to the tension source 500, and the various movement means. The storage unit 605 can comprise various types of data storage systems, including optical, magnetic, solid and other nonvolatile memories. The CPU is configured to carry out instructions in one or more control programs (software) stored in the memorising unit 605. In particular, the control programs are written such as to implement all the calibration, control and management methods that will be described in the following, enabling the CPU to perform all the steps of the methods.

In conclusion, it should be clarified that the apparatus 300 might include a plurality of operating devices 100 of the type described above, each of which can be set up to dispense a different material P, for example having a different colour, in order to create more complex decorations. The dispensing devices 100 of the plurality can be flanked to one another, or with the longitudinal axes A of the respective containing hoppers 105 aligned with one another, or one after another in a perpendicular direction to the longitudinal axes A, possibly slightly offset with respect to one another in order to obtain compositions of graphics which include several types of powders. In this case too, the plurality of dispensing devices 100 can be mounted fixed with respect to a mobile support plane 400, or can be mounted on movement means suitable for moving the plurality with respect to a fixed support plane 400, or both solutions.

Obviously, a technical expert in the sector might make numerous modifications of a technical-application nature to the apparatus 300 and the dispensing device 100, without its forsaking the ambit of the invention as it is claimed in the following.

REFERENCES

100 dispensing device

105 containing hopper

1 10 inlet mouth

1 15 outlet mouth

200 accumulating plane

205 falling edge

210 flexible blade

21 1 coating

212 lateral edge

213 countersinking

215 support structure

216 upper jaw

217 lower jaw

220 body of piezoelectric material

225 electric cable

230 weld seam

235 vibrating group

240 heating element

241 electrical connection

242 external body of the heating element

245 heating element

246 external body of the heating element

255 current generator

260 blower device

261 conveyor conduit

262 dispensing nozzle

263 tank

264 valve

265 heating element

270 hopper 271 conduit

300 apparatus

400 support plane

500 tension generator

600 electronic control unit

605 memorisation unit

A hopper longitudinal axis

S ceramic substrate

P material

Claims

1. A device (100) for dispensing a loose solid material (P), comprising a plurality of coplanar vibrating elements (210) arranged flanked to one another such as to restingly support the material (P) vertically flowing from an hopper (105), each of which is associated to a piezoelectric means (220) suitable for converting an electrical excitation signal into a mechanical vibration which can cause a fall of material (P) from the vibrating element (210), characterised in that it comprises heating means (240, 245) for heating the vibrating elements (210).

2. The device (100) of claim 1 , characterised in that the heating means comprise at least a heating element (240, 245) suitable for emanating heat.

3. The device (100) of claim 2, characterised in that the heating element (240) is configured such as to heat an entire plurality of the vibrating elements (210).

4. The device (100) of claim 2, characterised in that the heating means comprise plurality of the heating elements (245), each of which is configured such as to heat a respective vibrating element (210).

5. The device (100) of any one of the preceding claims, characterised in that the heating means (240) are configured such as to heat a structure (215) of a heat-conductive material suitable for support the plurality of vibrating elements (210).

6. The device (100) of any one of the preceding claims, characterised in that it comprises means (260) for cleaning the vibrating elements (210).

7. The device (100) of claim 6, characterised in that the cleaning means comprise at least a blower device (260) suitable for blowing an air current onto the vibrating elements (210).

8. The device (100) of claim 7, characterised in that the blower device (260) is associated to means (270, 271) for adding a dry powder material to the air current.

9. The device (100) of any one of the preceding claims, characterised in that the vibrating elements (210) are provided with a coating (211) of non-stick material.

10. The device (100) of any one of the preceding claims, characterised in that each vibrating element (210) is conformed such as to exhibit a reduced thickness at the lateral sides (212) which face the adjacent vibrating elements (210).

11. A functioning method of a device (100) for dispensing a loose solid material (P), the device (100) comprising a plurality of vibrating elements (210) arranged flanked such as to restingly support the material (P), each of which plurality of vibrating elements (210) is associated to a piezoelectric means (220) suitable for converting an electric excitation signal into a mechanical vibration which can cause a fall of material (P) from the vibrating element (210), characterised in that the functioning method comprises a step of heating the vibrating elements (210).

12r The method of claim 11 characterised in that the heating step comprises heating the vibrating elements (210) to a temperature comprised between 30°C and 50°C.

13. The method of any one of claims 11 , 12, characterised in that it comprises a step of cleaning the vibrating elements (210).

14. The method of any one of claims from 11 to 13 characterised in that the cleaning step comprises blowing an air current onto the vibrating elements (210).

15. The method of claim 15, characterised in that a dry powder material is added to the air current.