Technical Field

The present invention relates to a piece of equipment for the decoration of ceramic artifacts.

Background Art

In the decoration processes of ceramic artifacts, such as tiles and the like, the density and viscosity of the glaze used play a major role, as they significantly affect how the glaze itself is applied and the quality of the decoration obtained. For this reason, it is easy to appreciate how crucial it is to obtain a correct measurement of these properties in order to be able to optimize the subsequent phase of glaze application on the artifacts to be decorated.

In this regard, such measurements are nowadays made either manually by particularly sophisticated and expensive tools or by empirical tools of the type of a Ford cup.

Specifically, the latter tool consists of a hollow body provided with an inlet opening and with an outlet opening of the working liquid the viscosity of which is to be measured and having a predefined volume. This tool makes it possible to uniquely determine the viscosity of the liquid flowing through it by measuring the time it takes for the liquid to flow completely through the outlet opening.

However, the use of these tools is not without drawbacks.

In fact, taking measurements manually most often returns inaccurate and unreliable results.

Indeed, it is easy to appreciate how, given the completely manual nature of the measurement, the likelihood of errors or inaccuracies on the part of the person using the tools is very high.

In this case, the error made would go on to affect all subsequent activities involving the use of the measured parameter, jeopardizing its proper success.

In addition to all this, should the glaze have a different density from that suitable for carrying out a particular technological operation, the operator should add appropriate amounts of one or more liquids to an extent that would bring it to the desired value of density.

This turns out, however, to be a particularly complicated task to complete and marked by a high probability of error on the part of the operator.

It also turns out to be of primary importance, in the decoration processes of ceramic artifacts, to have on hand, and therefore ready for use, an adequate amount of glaze having the desired density and viscosity characteristics so as to meet the production requirements without incurring unwanted machine downtime. In fact, the machines for the decoration of ceramic artifacts of known type comprise a device for dispensing the glaze that must be properly fed during the production phases.

Indeed, it seems evident that the glaze to be applied to the ceramic artifacts must be prepared in advance and that its rheological characteristics may change over time if it is not used, e.g., due to the evaporation of part of its aqueous component.

Document EP3421203A1 describes a piece of equipment for the decoration of ceramic artifacts that involves preparing glaze to be dispensed onto the product at a predefined density. Additional equipment for the decoration of ceramic artifacts is known from EP1127667A2, JPH09328380A and SU1126562A1.

Description of the Invention

The main aim of the present invention is to devise a piece of equipment for the decoration of ceramic artifacts which enables a glaze having the desired rheological characteristics to be prepared quickly, automatically and accurately and made available for use in order to meet production requirements.

Within this aim, one object of the present invention is to devise a piece of equipment which allows simplifying glaze density correction operations by releasing them as much as possible from the operator’s skills and attention.

Another object of the present invention is to devise a piece of equipment for the decoration of ceramic artifacts which can overcome the aforementioned drawbacks of the prior art within the framework of a simple, rational, easy and efficient to use as well as cost-effective solution. A piece of equipment for the decoration of ceramic artifacts according to the invention comprises: a machine for the decoration of ceramic artifacts provided with a plane for conveying ceramic artifacts and at least one glaze dispensing device, wherein the machine comprises at least one internal reservoir adapted to contain the glaze to be applied onto the ceramic artifacts and hydraulically connected to the glaze dispensing device, and at least one glaze preparation tank hydraulically connected to the internal reservoir, wherein the preparation tank is provided with at least one measuring device for measuring the density and/or viscosity of the glaze contained in the preparation tank itself

Preferably, transfer means of the glaze from the preparation tank to the internal reservoir are provided.

Preferably, the piece of equipment comprises at least one electronic unit operationally connected at least to the measuring device so as to identify a detected value of the density and/or viscosity of the glaze contained in the preparation tank.

Preferably, the electronic unit is operationally connected to the transfer means and is adapted to command the glaze to be sent from the preparation tank to the internal reservoir when the detected density and/or viscosity corresponds to a reference value of density and/or viscosity.

Preferably, the piece of equipment comprises at least one glaze feeding tank located between the internal reservoir and the preparation tank and hydraulically connected thereto.

Preferably, the transfer means comprise first transfer means of the glaze from the feeding tank to the internal reservoir and second transfer means of the glaze from the preparation tank to the feeding tank.

Preferably, the internal reservoir comprises acquisition means for acquiring the level of glaze within it and the electronic unit, operationally connected to these acquisition means and to the first transfer means.

Preferably, the electronic unit is programmed to command the first transfer means themselves so as to send an amount of glaze from the feeding tank to the internal reservoir which is proportional to the decrease in the level of glaze detected by the acquisition means with respect to a predefined maximum level. Preferably, the machine comprises pressurization means adapted to maintain the pressure within the internal reservoir substantially equal to a predefined value.

Preferably, the glaze dispensing device comprises at least one internally hollow container for collecting the glaze to be applied to the ceramic articles and provided with at least one set of through orifices for the outflow of the glaze, a roller housed within the container and operable in rotation around a relevant axis, wherein the volume positioned between the inner walls of the container and the roller defines a glaze containment chamber hydraulically connected to the internal reservoir by means of a glaze feeding circuit, the orifices protruding internally to the containment chamber, and wherein the roller is provided with at least one set of projections adapted to open and close the orifices in a sequential and cyclic maimer during the rotation of the roller itself to allow and prevent respectively the glaze from flowing out of the container.

Preferably, the feeding circuit comprises at least one feeding stretch communicating with the internal reservoir, at least one pair of glaze transfer stretches communicating with the axial ends opposite each other of the containment chamber and at least one return stretch communicating with the feeding tank and comprises first valve means positioned between each of the transfer stretches, the feeding stretch and the return stretch and operable to selectively set each of the transfer stretches in communication with the internal reservoir and with the feeding tank.

Preferably, the electronic unit is operationally connected to the first valve means and is programmed to activate, for a predefined time interval, one of the first valve means so as to set the feeding stretch in communication with the relevant transfer stretch and the other of the first valve means so as to set the relevant transfer stretch in communication with the return stretch.

Preferably, the feeding tank comprises sensor means adapted to detect the level of glaze therein and the electronic unit is operationally connected to the sensor means and is programmed to command the activation of the second transfer means when the level of the glaze in the feeding tank reaches a predefined minimum value with the detected density and/or viscosity of the glaze in the preparation tank equal to the reference density and/or viscosity.

Preferably, the measuring device comprises at least one hollow body defining a glaze containment compartment comprising an inlet port and an outlet port of the glaze, where the outlet port has a smaller transit section than that of the inlet port and is arranged on top of the preparation tank so as to discharge the glaze within it; weighing means associated with the hollow body; detecting means for detecting the level of glaze within the containment compartment; wherein the electronic unit is operationally connected to the weighing means and to the detecting means, the latter being adapted to send to the electronic unit at least a first signal relating to the weight of the hollow body when the glaze contained within the containment compartment reaches a first predefined level and at least a second signal relating to the weight of the hollow body when the glaze reaches a second predefined level lower than the first predefined level, the electronic unit being configured to calculate a value of glaze weight corresponding to the difference between the first signal and the second signal and to calculate the density of the glaze depending on the calculated value of weight and on the volume of the containment compartment positioned between the first predefined level and the second predefined level; and wherein the electronic unit comprises at least one programmable memory with at least the value of the volume of the containment compartment positioned between the first predefined level and the second predefined level; a timer associated with the electronic unit, the latter being configured to calculate the time interval elapsing between the sending of the first signal and the sending of the second signal and to calculate an identification value of the glaze viscosity depending on the calculated time interval.

Preferably, the second transfer means comprise at least one transfer duct and second pumping means arranged along the transfer duct, and the piece of equipment is provided with at least one hydraulic circuit comprising: the second means of transfer; second valve means arranged along the transfer duct and activated to selectively send the glaze to the feeding tank or to a first duct designed adapted to send the glaze contained in the preparation tank within the hollow body; at least one second duct adapted to introduce an additional liquid having a predefined density and/or viscosity within the preparation tank; programmable memory containing at least one reference value of density and/or viscosity and the value of density and/or viscosity of the additional liquid and the electronic unit being programmed to compare the reference value of density and/or viscosity with the detected density and/or viscosity and to command the introduction of the additional liquid within the preparation tank when the detected density and/or viscosity differs from the reference density and/or viscosity.

Preferably, the electronic unit is programmed to calculate an updated value of density and/or viscosity depending on the amount of the additional liquid introduced into the preparation tank and to command the introduction of the additional liquid within the preparation tank when the updated value of density and/or viscosity differs from the reference value of density and/or viscosity.

Preferably, the second valve means are operationally connected to the electronic unit, which is configured to activate the second valve means themselves so as to allow the glaze to transit towards the feeding tank when the detected value of density and/or viscosity or the updated value of density and/or viscosity corresponds to the reference value of density and/or viscosity.

Preferably, the electronic unit is configured to calculate the amount of additional liquid to be introduced within the preparation tank to obtain the reference value of density and/or viscosity depending on the detected value of density and/or viscosity of the glaze.

Preferably, the first duct and the second duct are communicating with each other and third valve means are provided which are positioned between them and operable to selectively allow the entry into the hollow body of one of either the glaze or the additional liquid. Preferably, the third valve means are operationally connected to the electronic unit, which is configured to activate the third valve means themselves so as to allow the transit of only the additional liquid towards the hollow body when the calculated value of density and/or viscosity or the updated value of density and/or viscosity is different from the reference value of density and/or viscosity. Preferably, the second valve means are arranged upstream of the third valve means with respect to the direction of flow of the glaze from the preparation tank towards the hollow body.

Preferably, a sensor is provided of the level of glaze contained in the preparation tank and adapted to send a signal to the electronic unit which is adapted to calculate a corresponding signal of volume.

Preferably, the sensor is adapted to send a signal to the electronic unit prior to the introduction of the additional liquid into the preparation tank and at the end of the introduction thereof.

Preferably, the piece of equipment comprises at least one collection tank of the glaze to be introduced into the preparation tank, conveying means for conveying the glaze from the collection tank into the preparation tank comprising sieving means for sieving the glaze, and comprises at least one recirculation tank adapted to collect the glaze dispensed from the glaze dispensing device and hydraulically connected by means of a recirculation duct to the collection tank.

Preferably, a method for the decoration of ceramic artifacts according to the invention comprises at least the phases of preparation of the glaze to be applied onto the ceramic artifacts to be decorated and of application of the prepared glaze onto the ceramic artifacts themselves.

Preferably, the phase of preparation comprises at least the phases of: introduction of the glaze within a preparation tank; detection of the glaze level within the preparation tank; calculation of the glaze volume corresponding to the detected level; measurement of the density and/or viscosity of the glaze contained in the preparation tank so as to identify a detected value of density and/or viscosity; comparison of the detected value of density and/or viscosity with a reference value of density and/or viscosity and, if different: calculation of the amount of additional liquid having predefined density and/or viscosity to be introduced within the preparation tank depending on the calculated volume to obtain the reference value of density and/or viscosity.

A method for the decoration of ceramic artifacts, comprising at least the following phases of: preparation of the glaze to be applied onto the ceramic artifacts to be decorated; application of the prepared glaze onto the ceramic artifacts; wherein the phase of preparation comprises at least the following phases of: introduction of the glaze within a preparation tank 8; detection of the glaze level within the preparation tank 8; calculation of the glaze volume corresponding to the detected level; measurement of the density and/or viscosity of the glaze contained in the preparation tank so as to identify a detected value of density and/or viscosity De; comparison of the detected value of density and/or viscosity De with a reference value of density and/or viscosity DR and, if different: calculation of the amount of additional liquid having predefined density and/or viscosity to be introduced within the preparation tank 8 depending on the volume calculated to obtain the reference value of density and/or viscosity DR.

Other characteristics and advantages of the present invention will become more apparent from the description of a preferred, but not exclusive, embodiment of a piece of equipment for the decoration of ceramic artifacts, illustrated by way of an indicative, yet non-limiting example, in the attached tables of drawings in which:

Figure 1 is a schematic representation of a piece of equipment according to the invention; Figure 2 is a schematic representation of the measuring device for the measurement of the density and/or viscosity of the piece of equipment in Figure 1.

Embodiments of the Invention

With particular reference to these figures, reference numeral 1 globally denotes a piece of equipment for the decoration of ceramic artifacts.

The piece of equipment 1 comprises at least one machine 2 for the decoration of ceramic artifacts comprising a plane for conveying ceramic artifacts, not shown in the figures, and at least one glaze dispensing device 4 for dispensing glaze on the ceramic artifacts.

According to the invention, the machine 2 comprises at least one internal reservoir 5 adapted to contain the glaze S to be applied onto the ceramic artifacts and hydraulically connected to the glaze dispensing device 4.

Still according to the invention, the piece of equipment 1 comprises at least one preparation tank 8 of the glaze S, hydraulically connected to the internal reservoir 5 by means of the transfer means 7, 9 of the glaze S. The preparation tank 8 is provided with at least one measuring device 10 for measuring the density and/or viscosity of the glaze S contained in the preparation tank itself.

In particular, the feeding tank 6 and the preparation tank 8 are arranged externally to the machine 2.

The piece of equipment 1 then comprises at least one electronic processing and control unit 11 operationally connected to at least the measuring device 10 so as to identify a detected value of the density and/or viscosity of the glaze De and at least to the transfer means 7, 9; the electronic unit 11 is adapted to command the glaze to be sent from the preparation tank 8 to the internal reservoir 5 when the detected density and/or viscosity De corresponds to a reference value of density and/or viscosity DR.

Depending on the embodiment, the electronic unit 11 can therefore be adapted to receive a signal from the measuring device 10 corresponding to the detected density and/or viscosity De or, as in the embodiment described below, it can itself be adapted to calculate the value of density and/or viscosity De. Advantageously, the piece of equipment 1 comprises at least one feeding tank 6 positioned between the preparation tank 8 and the internal reservoir 5 and hydraulically connected thereto. The transfer means 7, 9 comprise, in turn, first transfer means 7 of the glaze S from the feeding tank 6 to the internal reservoir 5 and second transfer means 9 of the glaze S from the preparation tank 8 to the feeding tank 6. Specifically, the electronic unit 11 is adapted to send the glaze S from the preparation tank 8 to the feeding tank 6 when the detected density and/or viscosity De corresponds to the reference density and/or viscosity DR. Appropriate stirring means are arranged within the feeding tank 6 which are adapted to move the glaze contained therein.

Preferably, the internal reservoir 5 comprises acquisition means 12 for acquiring the level of glaze S within it, e.g., of the optical type. The electronic unit 11 is operationally connected to the acquisition means 12 and to the first transfer means 7. The electronic unit 11 is programmed to command the first transfer means 7 so as to send an amount of glaze S from the feeding tank 6 to the internal reservoir 5 which is proportional to the decrease in the level of glaze detected by the acquisition means 12 with respect to a predefined maximum level.

In more detail, the first transfer means 7 comprise at least one transit channel 13 for the glaze along which first pumping means 14 are arranged, e.g., of the type of a peristaltic pump. The electronic unit 11 is then programmed to command the first pumping means 14 in such a way that the amount of glaze sent towards the internal reservoir 5 is the greater the distance of the level of glaze detected by the acquisition means 12 with respect to a predefined maximum level and vice versa.

Advantageously, the machine 2 also comprises pressurization means 15 adapted to maintain the pressure within the internal reservoir 5 substantially equal to a predefined value.

In more detail, the pressurization means 15 comprise at least a pressurization channel 15a communicating with the internal reservoir 5 and connectable to a source of pressurized air G and valve means 15b, arranged along the pressurization channel 15a, which are adapted to prevent the passage of air from the internal reservoir 5 to the source of pressurized air and to discharge the air to the outside when the pressure in the internal reservoir 5 exceeds a predefined limit value.

The pressurization means 15 and the first pumping means 14 work independently and synergistically with each other to maintain the pressure in the internal reservoir 5 substantially (i.e., except for the fluctuations due to the changing glaze level within it and the tolerances of the components used) constant.

In the preferred embodiment shown in the Figures, the glaze dispensing device 4 comprises at least one internally hollow container 16 for collecting the glaze S to be applied to the ceramic articles, wherein the container 16 is provided with at least one set of through orifices (not shown in detail in the Figures) for the glaze outflow and at least one roller (not shown in detail in the Figures) housed within the container 16 and operable in rotation around a relevant axis. The roller is provided with at least one set of projections adapted to open and close the orifices in a sequential and cyclic maimer during the rotation of the roller itself to allow and prevent respectively, the glaze from flowing out of the container 16. The volume positioned between the inner walls of the container 16, which has an elongated conformation, and the roller defines a glaze containment chamber 17 hydraulically connected to the internal reservoir 5 by means of a feeding circuit 18 of the glaze S.

Preferably, the feeding circuit 18 comprises at least one feeding stretch 18a communicating with the internal reservoir 5, at least one pair of glaze transfer stretches 18b communicating with two axial ends opposite each other of the containment chamber 17 and at least one return stretch 18c communicating with the feeding tank 6.

The feeding circuit 18 then comprises first valve means 19 positioned between each of the transfer stretches 18b, the feeding stretch 18a and the return stretch 18c, which are operable to selectively set each of the transfer stretches 18b in communication with the internal reservoir 5 and with the feeding tank 6. The first valve means 19 are, e.g., of the three-way solenoid valve type.

Appropriately, the electronic unit 11 is operationally connected to the first valve means 19 and is programmed to activate, for a predefined time interval, one of the first valve means 19 so as to set the feeding stretch 18a in communication with the relevant transfer stretch 18b and the other of the first valve means 19 so as to set the relevant transfer stretch 18b in communication with the return stretch 18c. In this way, the glaze contained in the internal reservoir 5 enters the containment chamber 17 where one of its axial ends is located and flows out of the opposite end, dragging with it any air bubbles and transferring them to the inside of the feeding tank 6.

This operation is generally carried out both during the filling phase of the initially empty containment chamber 17 and during any production voids.

Advantageously, the feeding tank 6 comprises sensor means, not shown in detail in the figures, adapted to detect the level of glaze therein. The electronic unit 11 is operationally connected to these sensor means and is configured to command the activation of the second transfer means 9 when the level of glaze in the feeding tank 6 reaches a predefined minimum value LMIN and when, at the same time, the detected density and/or viscosity De of the glaze in the preparation tank 8 is substantially equal to, i.e. within a predefined range, the reference density and/or viscosity DR.

In more detail, the second transfer means 9 comprise at least one glaze transfer duct 20 and second pumping means 21 arranged along the transfer duct itself and operationally connected to the electronic unit 11.

Similarly, the electronic unit 11 is configured to stop sending the glaze by means of the second transfer means 9 when the glaze within the feeding tank 6 reaches a predefined maximum level LMAX. In this regard, it should be noted that the predefined maximum level LMAX is identified so that the glaze contained in the internal reservoir 5 can also be conveyed within the feeding tank 6 in case of recirculation.

Additionally, the feeding tank 6 and the preparation tank 8 are hydraulically connected to each other by means of a recirculation channel 22 along which at least one solenoid valve 23 is arranged operationally connected to the electronic unit 11. Specifically, the electronic unit 11 operates the solenoid valve 23 to allow the recirculation of the glaze contained in the feeding tank 6 within the preparation tank 8.

Advantageously, the measuring device 10 comprises at least one hollow body 24 defining a containment compartment 25 provided with at least one inlet port 26 and at least one outlet port 27 of the glaze S, where the outlet port 27 has a smaller transit section than that of the inlet port 26 and is arranged on top of the preparation tank 8 so as to discharge the glaze within it.

The measuring device 10 then comprises weighing means 28 associated with the hollow body 24 and detecting means 29 for detecting the level of glaze within the containment compartment 25, where the electronic unit 11 is operationally connected to the weighing means 28 and to the detecting means 29.

More specifically, the detecting means 29 are adapted to send to the electronic unit 11 at least a first signal relating to the weight of the hollow body 24 when the glaze contained within the containment compartment 25 reaches a first predefined level Li and at least a second signal relating to the weight of the hollow body 24 when the glaze reaches a second predefined level L2 lower than the first predefined level Li.

The electronic unit 11 is configured to calculate a glaze weight value corresponding to the difference between the first signal and the second signal and to calculate the density of the glaze depending on the calculated weight value and on the volume of the containment compartment 25 positioned between the first level Li and the second level L2.

In addition, the electronic unit 11 comprises at least one programmable memory 30 with at least the value of the volume of the containment compartment 25 positioned between the first level Li and the second level L2.

The measuring device 10 also comprises at least one timer 31 associated with the electronic unit 11, which is configured to calculate the time interval elapsing between the sending of the first signal and the sending of the second signal and to calculate an identification value of glaze viscosity depending on the calculated time interval.

For this purpose, the hollow body 24 comprises a Ford cup 32 defining the outlet port 27 and thus arranged below the first and the second predefined levels L ₂ .

Preferably, the Ford cup 32 is a Ford cup of the type 4.

Specifically, the electronic unit 11 calculates an identification value of glaze viscosity depending on the time interval elapsed between sending the first signal and sending the second signal.

In more detail, the electronic unit 11 processes the time interval elapsed between sending the first signal and sending the second signal depending on the volume interposed between the first level Li and the second level L ₂ and compares the time interval thus processed with a preset reference time value and uniquely correlated to a respective viscosity identification value.

Appropriately, the electronic unit 11 processes the measured time value and compares it with a reference time value that is coded, e.g. based on the time values for a Ford cup, and identifies the viscosity value for a given density value.

The measured time value is thus found to identify the viscosity value of the liquid introduced into the hollow body 24.

More particularly, the electronic unit 11 processes the measured time interval depending on the ratio of the interposed and preset volume between the first level Li and the second level L ₂ to the reference volume of the Ford cup and whose relevant time values have been preset for different reference density values.

It should be noted in this regard that the special expedient of providing a timer associated with the electronic unit 11 and with a Ford cup 32 defining the outlet port 27 allows the electronic unit 11 to measure an identifying value of the glaze viscosity in a simple and intuitive maimer.

Usefully, the containment compartment 25 comprises at least one drainage gap 33 communicating with the outside and arranged at a higher height than the first level Li and adapted to allow the outflow of the glaze to the outside. The drainage gap 33 thus defines the maximum volume of glaze which can be contained within the containment compartment 25.

Appropriately, the piece of equipment 1 comprises a hydraulic circuit 34 for feeding the measuring device 10, wherein such hydraulic circuit 34 comprises second transfer means 9, second valve means 35 arranged along the transfer duct 20, a first duct 36 communicating with the second valve means 35 and adapted to send the glaze contained in the preparation tank 8 within the hollow body 24 and at least a second duct 37 adapted to introduce an additional liquid having predefined density and/or viscosity within the preparation tank 8.

The transfer duct 20 thus has a first stretch 20a communicating with the preparation tank 8 and a second stretch 20b communicating with the feeding tank 6 and between which the second valve means 35 are positioned, which in turn are also connected to the first duct 36. The second valve means 35 can be activated to selectively send the glaze within the feeding tank 6 or along the first duct 36.

The programmable memory 30 contains at least one reference value of density and/or viscosity DR and the value of density and/or viscosity of the additional liquid, and the electronic unit 11 is programmed to compare the reference value of density and/or viscosity DR with the detected value of density and/or viscosity De and to command the introduction of the additional liquid within the preparation tank 8 when the detected density and/or viscosity De differs from the reference density and/or viscosity DR.

More particularly, the electronic unit 11 is programmed to calculate an updated value of density and/or viscosity DA depending on the amount of the additional liquid introduced into the preparation tank 8 and to command the introduction of the additional liquid within the preparation tank 8 when the updated value of density and/or viscosity DA differs from the reference value of density and/or viscosity DR.

Specifically, the electronic unit 11 is configured to calculate the amount of the additional liquid to be introduced within the preparation tank 8 to obtain the reference value of density and/or viscosity DR depending on the calculated density and/or viscosity De of the glaze S.

Appropriately, the electronic unit 11 is operationally connected to the second valve means 35 and is configured to activate them so as to allow the transit of the glaze S towards the feeding tank 6 when the detected value of density and/or viscosity De or the updated value of density and/or viscosity DA corresponds to the reference value of density and/or viscosity DR.

In the embodiment shown in the figures, the first duct 36 and the second duct 37 communicate with each other and third valve means 38 are provided between them, where the third valve means 38 are operable to selectively allow the entry into the hollow body 24 of one of either the glaze or the additional liquid.

In more detail, the third valve means 38 are operationally connected to the electronic unit 11, which is configured to activate the third valve means themselves so as to allow the transit of only the additional liquid towards the hollow body 24 when the detected value of density and/or viscosity De or the updated value of density and/or viscosity DA is different from the reference value of density and/or viscosity DR.

The third valve means 38 are arranged downstream of the second valve means 35 with respect to the direction of flow D of the glaze from the preparation tank 8 towards the hollow body 24.

The second duct 37, on the other hand, is connectable to an additional liquid feeding source, e.g., to the water mains, by means of fourth valve means 39, which are operable to selectively set the second duct 37 in communication with the feeding source of the pressurized liquid A or to the outside in order to allow the expulsion of any air bubbles within it.

Preferably, the piece of equipment 1 comprises at least one sensor 40, e.g. of an optical type, of the level of glaze contained in the preparation tank 8, which is adapted to send a corresponding signal to the electronic unit 11, which is adapted to calculate a corresponding value of volume.

Specifically, the sensor 40 is adapted to send a signal to the electronic unit 11 both prior to the introduction of the additional liquid into the preparation tank 8 and at the end of the introduction thereof.

Advantageously, the piece of equipment 1 comprises at least one collection tank 41 of the glaze to be introduced into the preparation tank 8, conveying means 42 for conveying the glaze from the collection tank 41 to the preparation tank 8 comprising sieving means 43 for sieving the glaze.

In addition, the piece of equipment 1 comprises at least one recirculation tank 44 adapted to collect the glaze dispensed by the glaze dispensing device 4 and hydraulically connected by means of a recirculation duct 45 to the collection tank 41.

The operation of this invention is as follows.

Initially, i.e., before starting the decoration process of the ceramic artifacts, the preparation of glaze S to be sent to the glaze dispensing device 4 is carried out.

The glaze contained in the collection tank 41 is then sent, by means of the conveying means 42 that sieve it, into the preparation tank 8.

The glaze contained in the preparation tank 8 is, in turn, sent through the hydraulic circuit 34 into the measuring device 10 for measuring density and viscosity. The electronic unit 11 then calculates the density and/or viscosity of the glaze in the maimer described above until the detected value of density and/or viscosity De or the updated value of density and/or viscosity DA corresponds to that of the set reference density and/or viscosity DR.

At this point the glaze contained in the preparation tank 8 is sent to the feeding tank 6 by means of the second transfer means 9 until the preset maximum level LMAX is reached.

The glaze is then sent from the feeding tank 6 to the internal reservoir 5 by means of the first transfer means 7.

After the internal reservoir 5 has been filled, the glaze contained therein is sent within the containment chamber 17 of the glaze dispensing device 4. Since initially the containment chamber 17 is empty, the electronic unit 11 provides for the activation of the first valve means 19 so that one of them sets the feeding stretch 18a in communication with one of the transfer stretches 18b and the other of the transfer stretches 18b with the return stretch 18c. In this way, the glaze is introduced within the containment chamber 17 through one of its axial ends and exits through the opposite axial end, thus dragging the air contained in the containment chamber 17.

Following the filling of the containment chamber 17 and its complete de- bubbling, the electronic unit 11 activates the first valve means 19 so that they both set the feeding stretch 18a in communication with the relevant transfer stretches 18b, so as to feed the containment chamber itself simultaneously through both its ends during the operation of the glaze dispensing device 4.

During the filling phase of the containment chamber 17 the level of glaze contained in the internal reservoir 5 decreases and is detected by the acquisition means 12 which communicate the corresponding reading by sending a signal to the electronic unit 11. The electronic unit 11 in turn commands the first pumping means 14 in such a way as to restore the maximum level in the internal reservoir 5 in the shortest possible time, whereby the corresponding peristaltic pump runs all the faster the greater the distance of the detected level of glaze from the predefined maximum level. At the same time, the pressurization means 15 activate to maintain the pressure in the internal reservoir 5 substantially constant, either by introducing pressurized air or by allowing it to vent to the outside.

Similar operation also occurs during the decoration phases, during which the level of glaze contained in the internal reservoir 5 undergoes changes.

In the event that production voids occur, detected by the electronic unit 11, the latter is configured to intervene on the first valve means 19 in a similar maimer to that described above so as to carry out the removal of any air pockets contained within the containment chamber 17.

At the moment when the level of glaze contained in the feeding tank 6 reaches the predefined minimum level LMIN, the electronic unit 11 returns glaze from the preparation tank 8 by operating the second transfer means 9.

More particularly, the electronic unit 11 activates the second pumping means 21 and the second valve means 35, so as to set the first stretch 20a in communication with the second stretch 20b, only when the detected value of density and/or viscosity De or the value of the updated density and/or viscosity DA corresponds to the reference density and/or viscosity DR. In the event of the density and/or viscosity of the glaze contained in the preparation tank 8 differs from the reference density and/or viscosity DR, the electronic unit 11 operates the third and fourth valve means 38 and 39 so as to introduce a predefined amount of additional liquid within the preparation tank 8, while at the same time maintaining the second valve means 35 in the state that sets the first stretch 20a in communication with the first duct 36, so as to recirculate the glaze contained in the preparation tank 8 within the hollow body 24 following the introduction of the additional liquid within it.

It has, in practice, been ascertained that the described invention achieves the intended objects, and in particular, the fact is emphasized that the piece of equipment covered by the present invention due to the presence of a plurality of vessels which are separate from each other, namely, the preparation tank, the containment chamber and the reservoir within the machine for the decoration of artifacts, as well as the use of the measuring device for measuring the density and/or viscosity, makes it possible to prepare in an automated and reliable maimer the glaze to be used, so that it has the desired rheological characteristics and to make it ready for use.

In addition, the first pumping means and the pressurization means make it possible to maintain the level of glaze and pressure within the internal reservoir almost constant, so as to optimize the feeding of glaze itself to the dispensing device.

It is also pointed out that the special expedient of providing an electronic unit comprising at least one programmable memory with a reference value of density and/or viscosity DR, with a value corresponding to the volume of the containment chamber positioned between the first predefined level and the second predefined level and with a predetermined value of density and/or viscosity of an additional liquid, makes it possible to correct the density and/or viscosity of the glaze to a reference value automatically.

Finally, it is emphasized that the special expedient of detecting the level of glaze within the preparation tank so as to identify the corresponding volume of glaze and, depending on the latter figure, calculate the exact amount of additional liquid to be introduced, allows the reference value of density and/or viscosity to be reached in a single step, i.e., with only one introduction of the additional liquid.

Last but not least, the use of a timer associated with the electronic unit and a Ford cup makes it possible to measure an identification value of the viscosity of a liquid.