Technical field

This invention relates to an apparatus and a method for making finished or semi-finished ceramic products.

Background art

In the ceramic manufacturing industry, the raw ceramic material, for example, from clay quarries, is basically subjected to two main process: grinding and pressing. Examples of grinding in the context of the manufacture of ceramic products are described in patent documents RE2003A000013 and RE2006A000089 in the name of the present Applicant..

Grinding is performed by mills which can work material that is dry or has a certain moisture content. More specifically, it is important that the material leaving the mill, before pressing, has a predetermined moisture content. The moisture content can therefore be varied by adding water into the mill. The prior art solutions therefore comprise a supply duct for feeding water into the mill and a conveyor for transporting the raw ceramic material into the mill. The amount of water fed into the mill is estimated on the basis of a static value of moisture content of the raw ceramic material, for example, obtained from data sheets of the materials.

These apparatuses and methods, however, have considerable disadvantages in terms of process quality because approximating the moisture content means that the material leaving the mill varies greatly in moisture content. In effect, the raw ceramic material varies considerably from one site to another and even within the same site. Approximating the moisture content can therefore lead to rather substantial errors.

Other examples of known systems for grinding in the production of ceramic products are provided in the following patent documents: EP2465611A1 , CN107127024A, CN106925415A, DE19719696A1 ,

WO201 3168115A1 , US2020378903A1 .

The system described in document EP2465611 also includes a sensor to measure the humidity of the mixture of raw materials. However, this system does not allow to effectively detect humidity, nor to effectively control the process.

Disclosure of the invention

The aim of this invention is to provide an apparatus and a method for making finished or semi-finished ceramic products to overcome the above mentioned disadvantages of the prior art.

This aim is fully achieved by the apparatus and method of this disclosure as characterized in the appended claims.

According to an aspect of it, this disclosure provides an apparatus for making finished or semi-finished ceramic products.

The apparatus comprises a water tank. The apparatus comprises a control unit. The apparatus comprises a grinding unit.

The grinding unit comprises a mill. The mill is configured to receive a raw ceramic material (hereinafter also referred to simply as “material”). The mill is configured to grind the material. The mill is configured to mix the material with water.

The grinding unit comprises a supply duct. The supply duct is connected to the water tank. The supply duct is connected to the mill to feed a quantity of water into it.

The apparatus comprises a conveyor. The conveyor is configured to transport the raw ceramic material along a conveyor path in a conveying direction oriented from a pickup zone to the grinding unit.

The apparatus comprises a measuring device. The measuring device is positioned upstream of the mill, along the conveyor path of the material. The measuring device is configured to capture a measurement signal representing a moisture content of the material being transported. The measuring device is configured to send the measurement signal to the control unit.

The control unit is programmed to derive a value of moisture content of the material, based on the measurement signal. That is, the control unit is programmed to derive the moisture value of the material, also based on the perturbed reference signal.

That way, the apparatus is provided with a value that is a reliable indication of the moisture content of the raw ceramic material and that the apparatus can use to discriminate different operations to be carried out on the material.

In a preferred embodiment, the control unit is programmed to control a quantity of water to be carried to the mill, based on the derived value of the moisture content.

In an embodiment, the apparatus comprises a regulating element, preferably a pump (or a divider valve).

The regulating element can shut off the supply duct. The regulating element is configured to regulate the amount of water fed into the mill.

The control unit is programmed to compare the derived value of moisture content with a predetermined value of moisture content. The control unit is configured to generate drive signals representing the amount of water to be fed into the mill, based on the comparison between the derived value of moisture content and the predetermined value of moisture content.

More specifically, in an embodiment, the apparatus comprises a weigher. The weigher is located upstream of the mill. In other embodiments, the weigher is associated with the mill to measure a weight of the material inside the mill. In a preferred embodiment, the weigher is built into the conveyor to define a weighing conveyor belt.

The weigher is configured to measure the weight of the raw ceramic material conveyed into the mill. The weight may be measured continuously or discontinuously. The weigher is configured to send to the control unit a weight signal representing the weight of the raw ceramic material fed into the mill. The weigher is not an essential element in that the raw material might, in some apparatuses, be fed into the mill in such a way that the weight of the material remains constant. The weight would be saved in a memory of the control unit, making the presence of a weigher inessential for the purposes of this invention.

The presence of a weigher can, however, enhance the flexibility of the apparatus because it allows diversifying the quantities processed by the mill without adversely affecting the quality of the product. In such an embodiment, therefore, the control unit is programmed, based on the given value of moisture content and on the weight of the raw ceramic material, to determine a precise quantity of water that will bring the moisture content of the raw ceramic material to the predetermined value. In other words, based on the weight signal and on the value of moisture content, the control unit, determines a value of dry ceramic material and a value of existing water (which moistens the dry material). The control unit is programmed to determine a value of water to be added to the dry ceramic material to obtain the predetermined value of moisture content. The control unit is programmed to subtract the value of existing water from the value of water to be added, thereby obtaining the quantity of water to be fed to the mill.

The control unit is configured to send the drive signals to the regulating element to instruct it to send the quantity of water to the mill.

That way, the amount of water fed to the mill can be varied in order to keep the moisture content of the material leaving the mill at a constant value irrespective of the diversity of the raw ceramic material entering the mill.

Preferably, the measuring device is located, relative to the conveyor, on a first side, opposite to a second side, where the raw ceramic material is positioned. This allows reducing dimensions on the second side of the conveyor belt, increasing the amount of material that can be transported and avoiding contact between the measuring device and the material. The measuring device might, however, be located on the second side, spaced from the material, so as to prevent the conveyor belt from disturbing the measurements.

Therefore, the detection device is configured to detect the moisture content in the material without contact with it, that is, the detection device constitutes a contactless (moisture) sensor. In fact, the material is placed in the measurement space at a (predetermined) distance, with respect to the detection line.

In an embodiment, the apparatus comprises a levelling element. The levelling element is positioned at a levelling position along the conveyor path. The levelling element is configured to distribute the raw ceramic material on the conveyor so that the raw ceramic material defines a uniform thickness along a measuring direction, perpendicular to the conveyor path.

The measuring device is interposed, along the conveyor path, between the levelling position and the mill.

The levelling element thus allows obtaining repeatable measurements, where the thickness parameter is fixed and does not, therefore, influence the measurement performed with the measuring device.

It should be noted that in an embodiment, the apparatus comprises an additional conveyor to form a plurality of conveyors. The conveyors of the plurality are each connected to a corresponding pickup zone (for example, a silo) where the raw ceramic material is located. The conveyors of the plurality are each connected to the mill to feed a respective raw ceramic material. The raw ceramic materials stored in the different pickup zones may have similar (identical or assimilable) physical and chemical properties or different physical and chemical properties to allow making finished or semi-finished ceramic products from multi-material recipes. In an embodiment, the apparatus also comprises an additional measuring device to form a plurality of measuring devices. In some examples, the apparatus comprises an additional weigher to form a plurality of weighers. The conveyors of the plurality are each associated with a corresponding measuring device of the plurality and with a corresponding weigher of the plurality.

In this embodiment, therefore, the control unit is programmed, for each conveyor, to receive a respective raw ceramic material being fed in and a corresponding value of moisture content. For each conveyor, the control unit is programmed to separate the quantity of dry material being fed in from the quantity of existing water, based on the weight of the respective raw ceramic material and the corresponding value of moisture content. The control unit is programmed to add up all the quantities of dry material fed by the plurality of conveyors to define a total quantity of dry material. The control unit is programmed to add up all the quantities of existing water to define a total quantity of existing water. The control unit determines the quantity of water to be fed to the mill based on the total quantity of dry material and the total quantity of existing water.

In an embodiment, the apparatus comprises an additional grinding unit to form a plurality of grinding units. Each grinding unit includes at least one respective supply duct and at least one respective mill. Furthermore, for each grinding unit, the device comprises at least one respective conveyor (or respective plurality of conveyors), at least one measuring device (or respective plurality of measuring devices and at least one respective weigher (or respective plurality of weighers).

In this embodiment, the control unit is programmed to receive the respective measurement signal from each measuring device.

Based on each measurement signal, the control unit is programmed to derive a value of moisture content of the raw ceramic material being transported on the corresponding conveyor.

The control unit is programmed to control a quantity of water to be carried to the corresponding mill, based on each derived value of moisture content. In an embodiment, the device comprises a generator for generating a high-frequency electrical measurement signal. It should be noted that the term “generator” is not intended to limit protection to a single generator but is used, more broadly, to denote a part whose function is to generate signals, thus including a single generator or a plurality of generators working in parallel.

The device comprises a measuring unit. The measuring unit includes a support structure. The measuring unit includes an electric circuit coupled to the support structure.

The electric circuit includes a measuring line (or measuring branch). The measuring line is connected to the generator. The measuring line operatively confronts the space region. The measuring line operatively confronts the space region to generate an electromagnetic field in the measurement space region in response to the measurement signal. Thus, the measurement signal is disturbed in response to an interaction of the electromagnetic field with the material. The measuring line preferably includes a respective high-frequency branch and a respective branch connected to ground.

The device comprises a control unit (or processing unit). It should be borne in mind that the control unit is not limited to a single computer, processor and/or microprocessor but may be functionally represented by a plurality of processors, even positioned at different locations, close to each other or remote from each other.

The control unit is connected to the measuring line to receive the disturbed measurement signal. The control unit is programmed to derive the value of the moisture content based on the disturbed measurement signal.

Advantageously, the device (the measuring unit) comprises a reference line (reference branch). The reference line is connected to the generator to receive a reference signal. The reference line is configured to generate, in response to the reference signal, an electromagnetic field that propagates into a reference space region, different from the measurement space region.

The control unit is connected to the reference line to receive the reference signal. Advantageously, the control unit is programmed to derive the value of the moisture content based also on the reference signal. Note that the humidity value derived on the basis of the reference signal is the humidity value of the material being measured.

When deriving the value of the moisture content, the reference line and the reference signal allow also including a reference that represents disturbances additional to those due to the material. In effect, since the reference line generates a field in a region where the material is not present, that region is influenced by disturbances additional to those of the material. Thus, by taking these disturbances into account, it is possible to isolate the disturbance due the material.

It should be noted that, according to a preferred embodiment, the detection device is spaced from the material which is subjected to inspection. Therefore, the device does not come into contact with the material but detects its humidity, always keeping at a distance. This provides the following advantages: (i) the detection device is not soiled and therefore does not risk being damaged by the effect of the material that could remain attached to it; (ii) the material is not touched and disturbed making the measurement more reliable and the process more streamlined.

Thus, in the measurement space region, the reference line and the detection line are spaced from the material being inspected. In other words, the material to be inspected is arranged in the measurement space region at a (predetermined) distance from the device, i.e. from the detection line and from the reference line; for example, a distance of at least 2 centimeters.

The generator is programmed to generate the measurement signal and/or the reference signal at a predetermined frequency. Advantageously, the control unit is programmed to perform, for that predetermined frequency, a pair of capture operations, including one to capture the measurement signal and one to capture the reference signal.

This aspect allows including, in each process to derive the value of the moisture content, an updated reference value, which is unlike simply calibrating the device statically.

In an embodiment, the generator is programmed to generate the measurement signal and the reference signal at a plurality of frequencies. Advantageously, the control unit is programmed to capture a plurality of pairs of capture operations, each corresponding to one frequency of the plurality of frequencies.

This allows making the instrument flexible and robust for different materials. In effect, by sweeping different frequencies, it is possible to identify the frequencies at which the material being examined causes an appreciable disturbance.

In an embodiment, the device comprises a direct line. The direct line connects the generator to the control unit to send a compare signal. The compare signal has the same physical properties as the measurement signal and/or the reference signal fed to the measuring line and to the reference line. Preferably, the compare signal has the same phase and amplitude as the measurement signal and/or the reference signal fed to the measuring line and to the reference line. The compare signal allows establishing the extent of the disturbance relative to the undisturbed signal generated by the generator.

The control unit is programmed to compare the phase and/or the amplitude of the disturbed measurement signal with the phase and/or the amplitude of the compare signal in order to derive a first value of a measurement phase displacement and/or a first value of a measurement attenuation.

The control unit is programmed to compare the phase and/or the amplitude of the disturbed reference signal with the phase and/or the amplitude of the compare signal in order to derive a first value of a reference phase displacement and/or a first value of a reference attenuation.

It should be noted that the term “phase displacement” is used to denote a phase difference between the compare signal and the measurement signal or the reference signal. The term “attenuation”, on the other hand, is used to denote a difference in amplitude between the compare signal and the measurement signal or the reference signal.

The control unit is programmed to derive the value of the moisture content based on the ratio between the first value of the measurement phase displacement and the first value of the reference phase displacement.

In addition or alternatively, the control unit is programmed to derive the value of the moisture content based on the ratio between the first value of the measurement attenuation and the first value of the reference attenuation.

In an embodiment, the control unit is programmed to capture the measurement signal in the absence of material in the space region. The control unit is programmed to derive a second value of the measurement phase displacement and/or a second value of the measurement attenuation, based on the measurement signal captured in the absence of material.

The control unit is programmed to capture the reference signal in the absence of material in the space region and to derive a second value of the reference phase displacement and/or a second value of the measurement attenuation, based on the reference signal captured in the absence of material.

The control unit is programmed to derive the value of the moisture content based also on the ratio between the second value of the measurement phase displacement and the second value of the reference phase displacement. In addition or alternatively, the control unit is programmed to derive the value of the moisture content based also on the ratio between the second value of the measurement attenuation and the second value of the reference attenuation.

These features further enhance the robustness of the system in that the signals captured in the absence of material on the measuring line and on the reference line are also taken into consideration.

In an embodiment, the generator and/or the control unit are selectively connected alternately to the measuring line and to the reference line by at least one deviator switch.

In an embodiment, the device comprises a first deviator switch element, movable between a measuring position, where the generator is connected to the measuring line, and a reference position, where the generator is connected to the reference line. The control unit is programmed to switch the first deviator switch element to the measuring position to receive the measurement signal, and to switch the first deviator switch element to the reference position to receive the reference signal. This embodiment advantageously allows using a single generator for both the measurement and the reference signal, which differ only in the line in which the same high-frequency signal is sent. Preferably, the first deviator switch comprises a relay.

According to an aspect of this disclosure, the device comprises a second deviator switch element. The second deviator switch element is located downstream of the measuring line and of the reference line along the electric circuit. The second deviator switch element is movable between a respective measuring position, where the control unit is connected to the measuring line, and a respective reference position, where the control unit is connected to the reference line. The control unit is programmed to switch the second deviator switch element to the measuring position to receive the measurement signal, and to switch the second deviator switch element to the reference position to receive the reference signal.

That way, it is possible to limit the number of control unit connections to a single connection (a single signal cable) which sends the disturbed measurement signal or the disturbed reference signal as a function of the position of the second deviator switch element.

In an embodiment, the first and second deviator switch elements are switchable in response to the control unit sending an activation signal. Preferably, in the absence of an activation signal, the first deviator switch element is set to the respective measuring position. Preferably, in the absence of an activation signal, the second deviator switch element is set to the respective reference position.

In an embodiment, for each measurement (capture operation), the control unit is programmed to send the activation signal to the first deviator switch element to switch the first deviator switch element to the reference position. For each measurement, the control unit is programmed to capture the reference signal.

For each measurement, the control unit is programmed to send the activation signal to the second deviator switch element to switch the second deviator switch element to the measuring position.

For each measurement, the control unit is programmed to capture the measurement signal.

For each measurement, the control unit is programmed to correct the measurement signal as a function of the reference signal.

In an embodiment, the measuring unit includes a first connector, configured to connect the measuring line and/or the reference line to the generator. In an embodiment, the measuring unit includes a second connector, configured to connect the measuring line and/or the reference line to the control unit.

Preferably, the measuring unit is symmetrical. In other words, the generator and the control unit can be connected alternatively to the first or the second connector arbitrarily. In yet other terms, the generator can be connected arbitrarily to the first or the second connector and the control unit is connectable to the connector to which the generator is not connected.

This aspect eliminates the risk of error assembling the measuring unit with regard to the control unit and the generator because there are no fixed connections that have to be observed.

According to an aspect of this disclosure, (independently of the presence of the reference line), the measuring line includes a signal electrode. The signal electrode has a flat shape. The signal electrode confronts the measurement space region.

The measuring line comprises a ground electrode. The ground electrode is spaced from the signal electrode. Preferably, the ground electrode partially surrounds the signal electrode.

The signal electrode is operatively interposed between the ground electrode and the measurement space region.

The flat shape of the signal electrode allows generating an electromagnetic field whose interaction with the material is optimal for obtaining a significant disturbance of the measurement signal.

Preferably, the signal electrode has a width of between 0.1 cm and 100 cm. Moreover, in addition or alternatively, the ratio between the width of the signal electrode and the gap between the signal electrode and the ground electrode is preferably between 10 and 2.

These features, combined with each other, allow obtaining an electromagnetic field whose field lines extend in an optimum manner for interaction with the material.

According to an aspect of this disclosure, the reference line includes a respective signal electrode. The signal electrode of the reference line confronts the reference space region.

The reference line comprises a respective ground electrode, spaced from the corresponding signal electrode.

The signal electrode of the reference line is operatively interposed between the corresponding ground electrode and the reference space region.

Preferably, the signal electrode of the reference line has a linear shape.

More specifically, the signal electrode of the reference line has a width of between 0.01 cm and 10 cm. Moreover, the ratio between the width of the signal electrode and the gap between the signal electrode and the ground electrode is between 10 and 2.

These features, unlike those of the measuring line, produce an electromagnetic field that is particularly circumscribed, with very concentrated field lines. This aspect allows the reference line to be influenced as little as possible by the external disturbances (and to maintain significance only with regard to disturbances due to the cables of the device) and allows the measuring line to be influenced as much as possible by the external disturbances.

According to an aspect of this disclosure, the device (the support structure) comprises a first wall. The first wall comprises a measuring surface. The measuring surface is associated with the measuring line. The measuring surface operatively confronts the measurement space region. The first wall comprises a supporting surface, opposite to the measuring surface.

In an embodiment, the device comprises a second wall. The second wall is associated with the reference line. The reference line is located on the second wall.

The device comprises a screening wall. The screening wall is interposed between the first and the second wall (relative to an axis perpendicular to the first and the second wall). The screening wall comprises a conductive element. The conductive element defines the ground electrode.

The signal electrode is spaced from the conductive element by a dielectric material.

In an embodiment, the screening wall defines a screening tank. The screening tank comprises a conductive coat, defining the ground electrode. Preferably, the conductive coat is a metallic paint.

The screening tank comprises an insulating cavity. The insulating cavity confronts the first wall so that the signal electrode is spaced from the conductive coat of the screening tank. The screening tank comprises an abutting wall. The abutting wall is in contact with the supporting surface of the first wall to support the measuring line, which is spaced from the screening tank.

In an embodiment, the device comprises a demodulator, configured to determine a phase and/or an amplitude of the measurement signal and/or of the reference signal.

Preferably, the measurement signal and the reference signal are analog signals. In this embodiment, the device comprises an analog-to-digital converter, located downstream of the measuring line, to convert the measurement signal and/or the reference signal into digital signals processable by the control unit.

In an embodiment, the device comprises a containing structure which houses at least the measuring unit. The containing structure is at least partly interposed between the measuring line and the measurement space region. Preferably, the containing structure is transparent to electromagnetic waves whose wavelength is in the aerial frequency range (for example, microwaves). In an embodiment, the containing structure is made of plastic. Preferably, the containing structure has a physical structure that does not disturb the measurement signal.

In an embodiment, the containing structure is a box, made preferably of opaque plastic.

According to an aspect of this disclosure, the present measuring device could be used in an apparatus for making finished or semi-finished ceramic products to measure the moisture content of a raw ceramic material or of semi-finished ceramic products; for example, before or after specific operations, for example, the step of mixing with water in the mill.

According to an aspect of it, this disclosure provides a method for remotely measuring a value of moisture content of a material positioned in a measurement space region.

The method comprises a step of generating a high-frequency measurement signal. The method comprises a step of transmitting the measurement signal to a measuring line which confronts the measurement space region. The method comprises a step, in response to the measurement signal, of generating an electromagnetic field that propagates into the measurement space region.

The method comprises a step of disturbing the measurement signal in response to an interaction of the electromagnetic field with the material disposed in the measurement space region.

The method comprises a step of receiving the disturbed measurement signal in a control unit. The method comprises a step of deriving the value of the moisture content, in the control unit, based on the disturbed measurement signal.

Advantageously, according to an aspect of this disclosure, the method comprises a step of generating a high-frequency electric reference signal. The method also comprises a step of transmitting the reference signal to a reference line that confronts a reference space region different from the measurement space region. The method comprises a step, in response to the reference signal, of generating an electromagnetic field that propagates into the reference space region. The method comprises a step of receiving the reference signal in a control unit. The method comprises a step of deriving, in the control unit, the value of the moisture content based also on the reference signal.

The generator generates the measurement signal and/or the reference signal at a predetermined frequency. In an embodiment of the method, the control unit performs a pair of capture operations, including one to capture the measurement signal and one to capture the reference signal.

Preferably, the generator generates the measurement signal and/or the reference signal at a plurality of frequencies. In such a case, the control unit preferably performs a plurality of pairs of capture operations, each corresponding to one frequency of the plurality of frequencies.

The method comprises a step of comparing. In the step of comparing, a direct line, which connects the generator to the control unit, sends a compare signal which has the same physical properties as the measurement signal and/or the reference signal fed to the measuring line and to the reference line.

In the step of comparing, the control unit compares the phase and/or the amplitude of the disturbed measurement signal with the phase and/or the amplitude of the compare signal in order to derive, as a result, a first value of a measurement phase displacement and/or a first value of a measurement attenuation.

The control unit compares the phase and/or the amplitude of the disturbed reference signal with the phase and/or the amplitude of the compare signal. The control unit derives a first value of a reference phase displacement and/or a first value of a reference attenuation.

The control unit derives the value of the moisture content based on the ratio between the first value of the measurement phase displacement and the first value of the reference phase displacement.

In addition or alternatively, the control unit derives the value of the moisture content based on the ratio between the first value of the measurement attenuation and the first value of the reference attenuation.

In an embodiment, the control unit captures the measurement signal in the absence of material in the space region. The control unit derives a second value of the measurement phase displacement and/or a second value of the measurement attenuation, based on the measurement signal captured in the absence of material.

The control unit captures the reference signal in the absence of material in the space region and derives a second value of the reference phase displacement and/or a second value of the measurement attenuation, based on the reference signal captured in the absence of material.

The control unit derives the value of the moisture content based also on the ratio between the second value of the measurement phase displacement and the second value of the reference phase displacement. In addition or alternatively, the control unit derives the value of the moisture content based also on the ratio between the second value of the measurement attenuation and the second value of the reference attenuation.

In an embodiment, the method comprises a step of switching.

In the step of switching, a first deviator switch element switches between a measuring position, where the generator is connected to the measuring line, and a reference position, where the generator is connected to the reference line.

In the step of switching, the control unit switches a first deviator switch element to a measuring position to receive the measurement signal, and switches the first deviator switch element to a reference position to receive the reference signal.

In the step of switching, a second deviator switch element switches between a respective measuring position, where the control unit is connected to the measuring line, and a respective reference position, where the control unit is connected to the reference line. In the step of switching, the control unit switches the second deviator switch element to the measuring position to receive the measurement signal, and switches the second deviator switch element to the reference position to receive the reference signal.

In an embodiment, for each measurement (capture operation), the control unit sends the activation signal to the first deviator switch element to switch the first deviator switch element to the reference position. For each measurement, the control unit captures the reference signal.

For each measurement, the control unit sends the activation signal to the second deviator switch element to switch the second deviator switch element to the measuring position.

For each measurement, the control unit captures the measurement signal. For each measurement, the control unit corrects (modifies, evaluates, processes) the measurement signal as a function of the reference signal.

In an embodiment, the method comprises a step of demodulating, in which a demodulator determines a phase and/or an amplitude of the measurement signal and/or of the reference signal.

In an embodiment, the method comprises a step of converting in which an analog-to-digital converter, located downstream of the measuring line, converts the analog measurement signal and/or the analog reference signal into digital signals processable by the control unit.

According to an aspect of it, this disclosure provides a device for metering and/or weighing one or more raw ceramic materials, comprising:

- the conveyor, which is configured to receive the raw ceramic material from the pickup zone and to transport the raw ceramic material into the mill;

- the measuring device, associated with the conveyor and configured to measure a value of moisture content of the raw ceramic material transported on the conveyor, the measuring device including one or more of the features described in this disclosure;

- the control unit, configured to determine a quantity of water to be fed into the mill based on the value of moisture content and on the predetermined value of moisture content.

In a preferred embodiment, the device for metering and/or weighing raw ceramic material also comprises a weigher, associated with the conveyor and configured to determine a weight value of the raw ceramic material transported on the conveyor. Further, in this embodiment, the metering device is configured to calculate the quantity of water based also on the weight value received.

Obviously, if there are at least two materials, the metering and/or weighing device may include a plurality of conveyors, each of which includes a respective measuring device and a respective weigher.

According to an aspect of it, this disclosure provides a method for making finished or semi-finished ceramic products.

The method comprises a step of feeding a raw ceramic material to a mill on a conveyor along a conveyor path. The method comprises a step of grinding the raw material in a mill.

The method comprises a step of feeding water to the mill through a supply duct.

The method comprises a step of mixing the ground, raw ceramic material with water.

The method comprises a step of capturing a measurement signal representing a moisture content of the raw ceramic material, by means of a measuring device positioned upstream of the mill along the conveyor path.

The method comprises a step of receiving the measurement signal in a control unit and deriving, through the control unit, a value of moisture content of the raw material, based on the measurement signal.

The method comprises a step of controlling, in which the control unit controls a quantity of water to be fed to the mill, based on the derived value of moisture content.

The method comprises a step of generating a high-frequency measurement signal by means of a generator.

The method comprises a step of transmitting the measurement signal to a measuring line which confronts the raw material.

The method comprises a step, in response to the measurement signal, of generating an electromagnetic field that propagates into the raw material.

The method comprises a step of disturbing the measurement signal in response to an interaction of the electromagnetic field with the raw material. The method comprises a step of receiving the disturbed measurement signal in the control unit.

The method comprises a step of deriving the value of the moisture content, in the control unit, based on the disturbed measurement signal.

In an embodiment, the step of capturing a measurement signal comprises a step of generating a high-frequency electric reference signal through the generator.

The step of capturing a measurement signal comprises a step of transmitting the reference signal to a reference line that confronts a space that has no raw ceramic material in it.

The step of capturing a measurement signal comprises a step, in response to the reference signal, of generating an electromagnetic field that propagates into the region without material in it.

The step of capturing a measurement signal comprises a step of receiving the disturbed reference signal in the control unit.

The step of capturing a measurement signal comprises a step of deriving, in the control unit, the value of the moisture content based also on the disturbed reference signal.

Brief description of drawings

These and other features will become more apparent from the following description of a preferred embodiment, illustrated by way of non-limiting example in the accompanying drawings, in which:

- Figures 1A and 1 B schematically illustrate a first embodiment and a second embodiment of an apparatus for making finished and semi-finished ceramic products;

- Figure 2 schematically illustrates a device according to this disclosure for measuring a value of moisture content of a material;

- Figure 3 shows a top perspective view of the device of Figure 2;

- Figure 4 shows a perspective view of the underside of the device of Figure 2;

- Figure 5 shows a perspective view of a screening tank of the device of Figure 3;

- Figure 6 is a functional diagram of the device of Figure 2;

- Figure 7 is an electrical diagram of the device of Figure 2.

Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, the numeral 100 denotes an apparatus for making ceramic products. The apparatus 100 comprises a water source 101 , for example, a water tank or a connection to the public water supply.

The apparatus comprises a control unit 4, configured to control the apparatus 100. The control unit 4 may comprise different processors located also in different zones of the apparatus 100 to control a certain group of components of the apparatus 100. In other embodiments, on the other hand, all the controls of the control unit 4 may be centralized in a remote supervisor connected to each component of the apparatus 100 to be controlled.

The apparatus 100 comprises a grinding unit 102. The grinding unit 102 is configured to receive a raw ceramic material MG and to grind it down to a predetermined grain size.

The grinding unit 102 (the apparatus 100) comprises a pickup device 1021 , configured to pick up the raw material MG from a pickup zone ZP. In an embodiment, the pickup zone ZP might be a quarry from which the raw material MG is dug out directly. In other embodiments, on the other hand, the pickup zone ZP is a storage zone where the raw material MG, after being quarried, is stored temporarily before being picked up by the pickup device 1021. For example, the pickup zone ZP might include a silo in which the material is stored before being picked up and transported elsewhere.

The grinding unit 102 (the apparatus 100) comprises a mill 1022. The mill 1022 is configured to grind the raw material MG. For example, in one embodiment, the mill 1022 is a rotary cylindrical body which houses grinding members which are made of a material greater in hardness than the raw material MG and which, on impact with the raw material MG, crush and grind the raw material MG. Grinding in the mill 1022 may be carried out under dry or, preferably, wet conditions. In wet grinding, the mill 1022 is configured to mix the raw material MG with water to a predetermined value of moisture content (to make what is known, in the jargon of the trade, as “slip”). For this purpose, the grinding unit 102 (the apparatus 100) comprises a supply duct 1023, configured to feed a quantity of water to the mill 1022. The supply duct 1023 runs from the water source 101 to the mill 1022.

In a preferred embodiment, the apparatus 100 comprises a pressure head element 1024, preferably a pump, configured to provide the water with a pressure head high enough to reach the mill 1022. The pressure head element 1024 is connected to the control unit 4 to receive from the latter drive signals 401 representing a quantity of water to be pumped into the mill 1022 through the pressure head element 1024.

The quantity of water to be pumped into the mill 1022 depends on the moisture content of the raw material MG and on the predetermined value of moisture content.

The grinding unit 102 (the apparatus 100) comprises a conveyor 1025 configured to transport the raw material MG from the pickup zone ZP to the mill 1022 along a conveyor path PT. The conveyor 1025 is preferably a conveyor belt including an upper section 1025A and a lower section 1025B. The raw material MG is placed on the upper section 1025A of the conveyor belt 1025 by the pickup device 1021. The conveyor belt terminates at an opening in the mill 1022 to feed the raw material MG therein.

In an embodiment, the apparatus 100 comprises a levelling element 1026. The levelling element 1026 is configured to level the raw material MG on the conveyor 1025 so that the thickness of the raw material MG is uniform along a measuring direction DR perpendicular to the conveyor belt 1025. In an embodiment, the levelling element 1026 is a levelling blade including a levelling end 1026A proximal to the conveyor 1025. More specifically, the distance along the measuring direction DR between the levelling end 1026A and the first section 1025A of the conveyor 1025 defines the uniform thickness of the raw material MG on the conveyor 1025. The presence of the levelling element 1026 thus allows defining a levelled zone ZL of the conveyor 1025, where the thickness of the raw material MG along the conveyor path PT is uniform, and a zone to be levelled ZDL, where the thickness of the raw material MG along the conveyor path PT is not uniform.

In an embodiment, the levelling element 1026 is located along the conveyor path PT, at a levelling position PLV, and confronts the first section 1025A of the conveyor belt 1025. In other words, in an embodiment, the levelling element 1026, directly confronts the raw material MG.

More specifically, in an embodiment, the apparatus comprises a weigher 1028. The weigher 1028 is located upstream of the mill. Preferably, the weigher 1028 is built into the conveyor 1025 to define a weighing conveyor belt.

The weigher 1028 is configured to measure the weight of the raw ceramic material conveyed into the mill 1022. The weight may be measured continuously or discontinuously. The weigher 1028 is configured to send to the control unit a weight signal S5 representing the weight of the raw ceramic material MG fed into the mill 1022.

In such an embodiment, therefore, the control unit is programmed, based on the given value of moisture content and on the weight of the raw ceramic material MG, to determine a precise quantity of water to bring the moisture content of the raw ceramic material to the predetermined value. In other words, based on the weight signal S5 and on the value of moisture content, the control unit, determines a value of dry ceramic material and a value of existing water (which moistens the dry material). The control unit is programmed to determine a value of water to be added to the dry ceramic material to obtain the predetermined value of moisture content. The control unit is programmed to subtract the value of existing water from the value of water to be added, thereby obtaining the quantity of water to be fed to the mill.

In an embodiment, the apparatus might be configured to work with finished or semi-finished, multi-material ceramic products. In such a case, the apparatus comprises a plurality of conveyors 1025. These conveyors 1025 each comprise a respective measuring device 1 , configured to determine a value of moisture content of the raw ceramic material transported on them, and a corresponding weigher 1028, configured to determine a weight of the raw ceramic material transported on them. Each conveyor 1025 of the plurality is connected to a central conveyor 1025’ which terminates in the mill 1022, where it releases the raw ceramic materials which it has received from the plurality of conveyors 1025.

For each measuring device 1 of each conveyor 1025, the control unit receives a measured value of moisture content (or a signal representing the moisture content on the basis of which the control unit itself determines the value of moisture content). For each weigher 1028 of each conveyor 1025, the control unit receives the weight signal S5 representing the weight of the material transported on the conveyor.

The control unit is programmed to calculate the quantity of water to be added into the mill 1022 based on the weight signals S5 and on the values of moisture content received.

In an embodiment, the apparatus 100 comprises a measuring device 1. The measuring device 1 is configured to capture a measurement signal S1 , ST. The measuring device 1 is configured to send the measurement signal S1 , ST to the control unit 4. The control unit 4 is programmed to derive a value of moisture content based on the measurement signal S1 , ST.

The measuring device 1 is located along the conveyor path PT to intercept the raw material MG before it is fed into the mill 1022. Preferably, the measuring device is located downstream of the levelling element 1026 along the conveyor path. More specifically, the measuring device 1 is located in the levelled zone ZL of the conveyor 1025 so as to capture the measurement signal S1 , ST where the thickness of raw material MG is constant, and can thus comply with the requirement of measurement repeatability. In an embodiment, the measuring device 1 confronts the second section 1025B of the conveyor belt 1025. In other words, in an embodiment, the measuring device 1 does not directly confront the raw material MG.

In an embodiment, the apparatus 100 comprises a presence sensor 1027. The presence sensor 1027 is configured to capture a presence signal S4 representing the presence or absence of the raw material MG on the conveyor 1025. In an embodiment, the presence sensor 1027 could be a laser sensor, a distance sensor, an optical sensor, a camera or any other means configured to capture a physical quantity (flight time, image data) from which an information item representing the presence or absence of the raw material MG can be derived.

The presence sensor 1027 is configured to send the presence signal S4 to the control unit 4. Based on the presence signal S4, the control unit 4 is programmed to infer whether or not the raw material MG is present or absent on the conveyor 1025.

For example, if the presence sensor 1027 is a camera, the control unit uses suitable image processing algorithms to process the image data captured by the presence sensor 1027, to understand whether the conveyor 1025 has raw material MG on it.

Preferably, the presence sensor 1027 is located upstream of the measuring device 1 along the conveyor path PT.

In an embodiment, the presence sensor 1027 confronts the first section 1025A of the conveyor belt 1025. In other words, in an embodiment, the presence sensor 1027, directly confronts the raw material MG.

The control unit 4 is programmed to capture, through the measuring device 1 , a no-load measurement signal S1 ”, that is to say, a measurement signal S1 in the absence of raw material MG on the conveyor 1025.

Thus, based on the presence signal, the control unit 4 is able to decide when to perform the measurement with the measuring device 1 to capture the no-load measurement signal S1 ”. In an embodiment, the control unit 4, once it has derived the value of moisture content of the raw material MG, is programmed to compare the derived value of moisture content with the predetermined value of moisture content. The control unit 4 is programmed to calculate the quantity of water to be fed into the mill 1022 based on the comparison between the derived value of moisture content and the predetermined value of moisture content, preferably based on the difference between the predetermined value of moisture content and the derived value of moisture content.

The control unit 4 therefore generates the drive signals 104 to be sent to the pressure head element 1024 to instruct it to send the correct quantity of water to the mill 1022.

An embodiment of the device 1 is described below by way of example.

It should be noted that for the purposes of this disclosure, the following considerations apply:

- the measurement space region R1 is the region of space in which the raw material MG is positioned;

- the reference space region R2 is the region of space in which there is no raw material MG, for example, the space region in which the conveyor 1025 is not present;

- the material M is the raw material MG.

In light of these explanations, the device 1 is a device for remotely measuring a value of moisture content of a material M positioned in a space region R1 .

The device 1 comprises a generator 2, configured to generate a signal that is characterized by a predetermined frequency, a predetermined amplitude and a predetermined phase.

The device 1 comprises an input line 11 from the generator.

The device 1 comprises a measuring unit 3. To perform the measurement, the measuring unit 3 is located in the proximity of the material M to be analysed.

The input line 11 comprises a signal line 11 A and a ground line connected to the ground of the generator 2 to screen an electromagnetic field generated by the signal line 11 A.

The measuring unit 3 comprises a first connector 31 . The input line 11 is connected to the first connector 31 to send the signal from the generator 2 to the measuring unit 3.

In an embodiment, the measuring unit 3 comprises a first deviator switch 32, preferably a relay, configured to selectively direct the signal generated by the generator 2.

The measuring unit 3 comprises a measuring line 33. The measuring line 33 confronts the space region R1. The measuring line 33 comprises a respective signal electrode 33A and a ground electrode 33B.

In an embodiment, the measuring unit 3 comprises a reference line 34. The reference line 34 confronts a reference space region R2 which is distinct and spaced from the space region R1. The reference line 34 comprises a respective signal electrode 34A and a ground electrode 34B.

The measuring line 33 and the reference line 34 are connected to the first deviator switch 32 to selectively receive the signal generated by the generator 2. More specifically, when the first deviator switch 32 directs the signal to the measuring line 33, the signal is a measurement signal S1. Otherwise, when the first deviator switch 32 directs the signal to the reference line 34, the signal is a reference signal S2.

The signal electrode 33A of the measuring line 33 is configured to generate an electromagnetic field in response to the passage of the measurement signal S1 in the space region R1. That way, the electromagnetic field strikes the material M, which interacts with the electromagnetic field and thus disturbs the measurement signal S1 . The disturbance depends on the physical properties of the material M, specifically the moisture content of the material M.

In an embodiment, the signal electrode 34A of the measuring line 34 is configured to generate an electromagnetic field in response to the passage of the reference signal S2 in the reference space region R2. It should be noted that the ground electrode 33B of the measuring line 33 is interposed between the signal electrode 33A of the measuring line 33 and the signal electrode 34A of the reference line 34. That way, the electromagnetic field generated in response to the measurement signal S1 does not affect the reference space R2 or the reference line 34 and is not therefore disturbed by the components of the reference line 34 or by material present in the reference space region R2.

In an embodiment, the device 1 (the measuring unit 3) comprises a second deviator switch 35, preferably a relay.

In an embodiment, the measuring line 33 and the reference line 34 converge towards the second deviator switch 35.

The measuring unit comprises a second connector 36.

The device comprises a control unit 4. The device 1 comprises an output line 12. The output line 12 is connected to the control unit 4 and to the second deviator switch 35. The output line 12 is connected to the control unit 4 and to the second connector 36 which is in turn connected to the second deviator switch 35.

Thus, the control unit 4 is configured to selectively receive the measurement signal S1 or the reference signal S2, based on the position of the first deviator switch 32 and/or of the second deviator switch 35.

More specifically, the first deviator switch 32 is movable between a respective measuring position PR1 , where the generator 2 is connected to the measuring line 33, and a respective reference position PF1 , where the generator 2 is connected to the reference line 34. Further, the second deviator switch 35 is movable between a respective measuring position PR2, where the control unit 4 is connected to the measuring line 33, and a respective reference position PF2, where the control unit 4 is connected to the reference line 34.

The control unit 4 is configured to send to the first deviator switch 32 and/or to the second deviator switch 35 respective drive signals 401 to drive the first deviator switch 32 and/or the second deviator switch 35 to move between the respective measuring position PR1 , PR2 and the respective reference position PF1 , PF2.

More specifically, the control unit is programmed to receive the measurement signal S1 when the first deviator switch 32 and the second deviator switch 35 are at the respective measuring positions PR1 , PR2. Further, in the presence of the reference line 34, the control unit 4 is configured to receive the reference signal when the first deviator switch 32 and the second deviator switch 35 are at the respective reference positions PF1 , PF2.

It should be noted that in a preferred embodiment, the control unit 4 is configured to send the drive signal 401 to energize the first deviator switch 32 or the second deviator switch 35 which switches its position responsive to being energized. The first and the second deviator switch 32, 35 thus include a default position between the measuring position PR1 , PR2 and the respective reference position PF1 , PF2.

In an embodiment, the default position of the first deviator switch 32 is the measuring position PR1 , while the default position of the second deviator switch is the reference position PF2. This avoids having closed circuits when not energized. Instead, this configuration allows connecting the generator 2 and the control unit 4 to each line by energizing only one between the first deviator switch 32 and the second deviator switch 35. By way of example, we may observe that to connect the measuring line 33, the control unit 4 is programmed to send the drive signal 401 (activation signal, energizing signal) to the second deviator switch 35 which, responsive to receiving the drive signal 401 , switches from the reference position PF2 to the measuring position PR2. Thus, since the first deviator switch 32 is at the measuring position PR1 (default position), the measuring line 33 is connected to the generator 2 and to the control unit 4 to receive the disturbed measurement signal S1 ’.

When the control unit 4 captures the disturbed reference signal S2’, on the other hand, it sends the drive signal 401 to the first deviator switch 302 (without energizing the second deviator switch 35) which, responsive to receiving the drive signal 401 , switches to the reference position PF1. Thus, since the second deviator switch 35 is at the reference position PF2 (default position), the reference line 34 is connected to the generator 2 and to the control unit 4 to receive the disturbed reference signal S2’.

The control unit 4 is preferably configured to send the drive signal 401 in succession first to the first deviator switch 32 to capture the disturbed reference signal S2’, and then to the second deviator switch 35 to capture the disturbed measurement signal ST so as to capture, for each measurement, a pair of signals, defined by the disturbed measurement signal and the disturbed measurement signal ST, S2’.

Hence, the control unit 4 receives a disturbed measurement signal ST, that is to say, the measurement signal S1 that has been disturbed by the presence of the material M and/or by the presence of cables (components of various kinds) of the device 1. The control unit 4 is programmed to derive the value of the moisture content based on the disturbed measurement signal ST. More specifically, in an embodiment, the control unit 4 is programmed to receive a disturbed reference signal S2’, that is to say, the reference signal S1 that has been disturbed by components of various kinds (by the cables) of the device 1 .

The control unit 4 is programmed to derive the value of the moisture content based on the disturbed measurement signal ST and on the disturbed reference signal S2’.

The device 1 comprises a direct line 13, which connects the generator 2 directly to the control unit 4 so that the signal generated, (that is, a compare signal S3) which has the same properties as the signal that defines the measurement signal S1 and/or the reference signal S2 in the measuring unit 3, is sent directly.

The control unit 4 is programmed to derive the value of the moisture content based on a comparison between the compare signal S3 (that is, the undisturbed measurement signal S1 ) and the disturbed measurement signal S1 The control unit 4 is programmed to derive the value of the moisture content based on a comparison between the compare signal S3 (that is, the undisturbed reference signal S2) and the disturbed reference signal S2’.

In a preferred embodiment, therefore, to assess each value of moisture content, the control unit 4 has at least the following signals available to it: measurement signal S1 , reference signal S2 and compare signal S3.

In an embodiment, the control unit 4 is also programmed to capture a no- load measurement signal S1 ”, that is to say, the measurement signal S1 in the absence of material M in the space region R1 . Further, the control unit 4 is also programmed to capture a no-load reference signal S2”, that is to say, the reference signal S2 in the absence of material M in the space region R1 .

In an embodiment, the control unit is programmed to determine the value of the moisture content based on the compare signal S3, the disturbed measurement signal ST, the no-load measurement signal S1 ”, the disturbed reference signal S2’ and the no-load reference signal S2”.

In an embodiment, the control unit 4 is programmed to determine the value of the moisture content based on one or both of the characteristic parameters of the signals, namely phase and amplitude. More specifically, the control unit 4 is programmed to determine the value of the moisture content based on the phase F3 and/or the amplitude A3 of the compare signal S3, the phase FT and the amplitude AT of the disturbed measurement signal ST, the phase F1 ” and the amplitude A1 ” of the no- load measurement signal S1 ”, the phase F2’ and/or the amplitude A2’ of the disturbed reference signal S2’ and/or the phase F2” and the amplitude A2” of the no-load reference signal S2”.

In an embodiment, the control unit 4 is programmed to determine a first measurement phase displacement SFR1 , calculated as the difference between the phase FT of the disturbed measurement signal ST and the phase F3 of the compare signal S3. In an embodiment, the control unit 4 is programmed to determine a second measurement phase displacement SFR2, calculated as the difference between the phase F1 ” of the no-load measurement signal S1 ” and the phase F3 of the compare signal S3.

In an embodiment, the control unit 4 is programmed to determine a first reference phase displacement SFF1 , calculated as the difference between the phase F2’ of the disturbed reference signal S2’ and the phase F3 of the compare signal S3. In an embodiment, the control unit 4 is programmed to determine a second reference phase displacement SFF2, calculated as the difference between the phase F2” of the no-load reference signal S2” and the phase F3 of the compare signal S3.

In an embodiment, the control unit 4 is programmed to derive the value of the moisture content of the material M as a function of a phase indicative ratio RI1 , calculated as the ratio between the first measurement phase displacement SFR1 and the first reference phase displacement SFF1. In an even more advantageous embodiment, the control unit 4 is programmed to calculate a phase calibration parameter PC1 , calculated as the ratio between the second measurement phase displacement SFR2 and the second reference phase displacement SFF2. In such a case, the control unit 4 is programmed to derive the value of moisture content of the material M based on the ratio between the phase indicative ratio RI1 and the phase calibration parameter PC1 .

In an embodiment, the control unit 4 is programmed to determine a first measurement attenuation AR1 , calculated as the difference between the amplitude A1 ’ of the disturbed measurement signal S1 ’ and the amplitude A3 of the compare signal S3. In an embodiment, the control unit 4 is programmed to determine a second measurement attenuation AR2, calculated as the difference between the amplitude A1 ” of the no-load measurement signal S1 ” and the amplitude A3 of the compare signal S3.

In an embodiment, the control unit 4 is programmed to determine a first reference attenuation AF1 , calculated as the difference between the amplitude A2’ of the disturbed reference signal S2’ and the amplitude A3 of the compare signal S3. In an embodiment, the control unit 4 is programmed to determine a second reference attenuation AF2, calculated as the difference between the amplitude A2” of the no-load reference signal S2” and the amplitude A3 of the compare signal S3.

In an embodiment, the control unit 4 is programmed to derive the value of the moisture content of the material M as a function of an amplitude indicative ratio RI2, calculated as the ratio between the first measurement attenuation AR1 and the first reference attenuation AF1. In an even more advantageous embodiment, the control unit 4 is programmed to calculate an amplitude calibration parameter PC2, calculated as the ratio between the second measurement attenuation AR2 and the second reference attenuation AF2. In such a case, the control unit 4 is programmed to derive the value of moisture content of the material M based on the ratio between the amplitude indicative ratio RI2 and the amplitude calibration parameter PC2.

In an embodiment, the control unit 4 is programmed to derive the value of moisture content of the material M based on the ratio between the phase indicative ratio RI1 and the phase calibration parameter PC1 and based on the ratio between the amplitude indicative ratio RI2 and the amplitude calibration parameter PC2.

To sum up, the different embodiments set out above are represented by the following formulas:

Value of moisture content = f(SFR1/SFF1 ) = f(RI1 );

Value of moisture content = f(AR1/AF1 ) = f(RI2);

Value of moisture content = f((SFR1/SFF1) / (SFR2/SFF2)) = f(RI1/PC1 ); Value of moisture content = f((AR1/AF1 ) / (AR2/AF2)) = f(RI2/PC2).

It should be noted that in an embodiment, the control unit 4 includes one or more of the following parts:

- a control microprocessor 41 , configured to control the first deviator switch 32 and/or the second deviator switch 35;

- a drive unit 42, connected to the generator 2 (preferably through the microprocessor 41 ) to drive it to generate the signals and connected to the output line 12 to receive the disturbed signals;

- a demodulator 43, configured to derive the amplitude and phase value from a signal; more specifically, the demodulator is configured to determine the values of amplitude AT, A1 ”, A2’, A2” and A3 and the values of phase F1 ’, F1 ”, F2’, F2” and F3;

- an analog-to-digital converter 44, configured to receive the disturbed measurement signal S1 ’ and/or the disturbed reference signal S2’ in analog format and to convert it to digital format; the converter may be located downstream of the demodulator 43;

- a remote control terminal 45, connected (preferably through a wireless connection) to the drive unit 42 to receive the disturbed signals (preferably in digital format) and including a processor, configured to process the disturbed signals S1 ’, S2’ and the compare signal S3 to derive the value of moisture content of the material M.

In an embodiment, the microprocessor 41 is connected to the first deviator switch 32 and to the second deviator switch 35 by means of a first terminal strip 41 1 and a second terminal strip 412, respectively. The first terminal strip 411 comprises two terminals, connected to the microprocessor 41 and to respective control pins 321 of the first deviator switch 32. Thus, the microprocessor 41 sends the drive signals 401 to the control pins 321 of the first relay 32. The second terminal strip 412 comprises two respective terminals, connected to the microprocessor 41 and to respective control pins 351 of the second deviator switch 32. Thus, the microprocessor 41 sends the drive signals 401 to the control pins 351 of the second relay 35.

The device 1 comprises a support structure 5. The device 1 comprises a containing structure 6, configured to contain at least the measuring unit 3 and, in some embodiments, also the generator 2 and/or the control unit 4. Preferably, the containing structure 6 is transparent to microwaves. The containing structure 6 protects the measuring unit 3 from external agents.

The support structure 5 comprises one or more connectors 51 (for example, screws and/or bolts). The connectors 51 are connected to an external support on which the device 1 can be mounted. The support structure 5 is connected to the containing structure 6.

The support structure 5 comprises a first wall 52. The first wall 52 comprises a measuring surface 521 , confronting the space region R1 , and a supporting surface 522, opposite to the measuring surface 521. In an embodiment, the measuring line is at least partly disposed on (associated with) the first wall 52, specifically the measuring surface 521 . In effect, the signal electrode 33A of the measuring line is disposed on the measuring surface 521 to confront the space region R1 .

In an embodiment, the signal electrode 33A of the measuring line 33 has a flat shape. The ground electrode 33B includes a track which crosses the measuring surface 521 , running alongside the signal electrode 33A, at a first operating distance along the plane defined by the measuring surface 33A.

In an embodiment, the support structure 5 comprises a second wall 53. The second wall comprises a contact surface 531 and a reference surface 532, which confronts the reference space region R1 .

The reference line 34 is (at least partly) associated with the second wall 53, specifically the reference surface 532. More specifically, the signal electrode 34A and the ground electrode 34B of the reference line 34 are defined by two leads which are electrically isolated from each other.

In an embodiment, the support structure 5 comprises a screening wall 54. The screening wall 54 is interposed between the first and the second wall 52, 53, along a measuring direction DR perpendicular to the first wall 52 and to the second wall 53.

The screening wall 54 comprises:

- a top surface 541 , configured to come into contact with the contact surface 522 of the first wall 52;

- a bottom surface 542, configured to come into contact with the contact surface 531 of the second wall; - a first lateral wall 543, on which the first deviator switch 32 and/or the first terminal strip 411 are disposed;

- a second lateral wall 544, on which the second deviator switch 35 and/or the second terminal strip 412 are disposed.

In an embodiment, the top surface 541 comprises an abutting portion 541 A and a recessed portion 541 B that is defined by a corresponding cavity CV of the screening wall. The recessed portion 541 B is spaced at a third operating distance along the measuring direction. The electromagnetic field generated by the measuring line 33 in response to the measurement signal S1 depends on the first operating distance and/or on the third operating distance.

In an embodiment, the top surface 541 of the screening wall 54 is painted with a conductive paint, preferably a metallic paint. The abutting portion 541 A is in contact with the supporting surface 522 of the first wall 52. Furthermore, the track of the ground electrode 33B of the measuring line 33 is in contact with the paint coating of the screening wall 54 so that the entire painted wall defines the ground electrode 33B and thus screens the electromagnetic field in the measuring direction oriented towards the second wall 53.

In an embodiment, the cavity CV comprises a flat bottom CV1 , a first inclined portion CV2 and a second inclined portion CV2. The flat bottom CV1 is interposed, along a longitudinal direction L, perpendicular to the measuring direction DR, between the first inclined portion CV2 and the second inclined portion CV3. That way, the third operating distance increases along the first inclined portion, remains constant along the flat bottom CV1 and decreases again along the second inclined portion CV3.

In an embodiment, the first wall 52 comprises a first plurality of assembly holes 523. The second wall comprises a second plurality of assembly holes 533. The screening wall 54 comprises a third plurality of assembly holes 545. The first plurality of assembly holes and the third plurality of assembly holes house a first plurality of connectors 55 to fasten the first wall 52 to the screening wall 54. The second plurality of assembly holes and the third plurality of assembly holes house a second plurality of connectors 56 to fasten the second wall 53 to the screening wall 54.

In an embodiment, the first connector 31 is disposed on the first lateral wall 543. In an embodiment, the second connector 36 is disposed on the second lateral wall 544.

In an embodiment, the signal electrode and the ground electrode are shaped and/or spaced from each other in such a way that the impedance of the measurement signal is 50 Ohm.

In an embodiment, the device 1 is positioned at a conveyor which transports the material M along a conveying direction. The signal electrode 33A of the reference line is elongated along main direction of extension. In an embodiment, the device 1 is positioned relative to the conveyor in such a way that the main direction of extension of the signal electrode 33A of the measuring line is perpendicular to the conveying direction. In other embodiments, it may be positioned differently, for example, with the main direction of extension of the signal electrode 33A of the measuring line parallel to the conveying direction.

According to an aspect of the present description, the present disclosure aims also at protecting a device as indicated in the following paragraphs, identified with the respective alphanumeric references.

A1. A device (1 ) for remotely measuring a value of moisture content of a material (M) positioned in a measurement space region (R1), comprising:

- a generator (2) for generating a high-frequency electrical measurement signal (S1 );

- a measuring unit (3), including a support structure (5) and an electric circuit coupled thereto, the electric circuit including a measuring line (33), connected to the generator (2) and operatively confronting the space region (R1) to generate an electromagnetic field in the measurement space region (R1 ) in response to the measurement signal (S1), so that the measurement signal (S1) is disturbed in response to an interaction of the electromagnetic field with the material (M);

- a control unit (4), connected to the measuring line (33) to receive the disturbed measurement signal (S1 ’) and programmed to derive the value of the moisture content based on the disturbed measurement signal (S1 ’);

- a reference line (34), connected to the generator (2) to receive a reference signal (S2) and configured to generate, in response to the reference signal (S2), an electromagnetic field that propagates into a reference space region (R2), different from the measurement space region (R1), wherein the control unit (4) is connected to the reference line (34) to receive a disturbed reference signal (S2’) and is programmed to derive the value of the moisture content based also on the disturbed reference signal (S2’) (in other words, the control unit (4) is programmed to derive the value of the moisture content of the material (M), further based on the disturbed reference signal (S2 ')).

A2. The device (1 ) according to paragraph A1 , wherein the generator (2) is programmed to generate the measurement signal (S1) and the reference signal (S2) at a predetermined frequency and wherein the control unit (4) is programmed to perform, for that predetermined frequency, a pair of capture operations, including one to capture the measurement signal (S1) and one to capture the reference signal (S2).

A3. The device (1 ) according to paragraph A2, wherein the generator (2) is programmed to generate the measurement signal (S1) and the reference signal (S2) at a plurality of frequencies and wherein the control unit (4) performs a plurality of pairs of capture operations, each corresponding to one frequency of the plurality of frequencies.

A4. The device (1 ) according to any one of the preceding paragraphs, comprising a direct line (13) that connects the generator (2) to the control unit (4) to send a compare signal (S3) having the same phase and amplitude as the measurement signal (S1) and the reference signal (S2) fed to the measuring line (33) and to the reference line (34) and wherein the control unit (4) is programmed to: - compare the phase and/or the amplitude (F1 ’, A1 ’) of the disturbed measurement signal (S1 ’) with the phase and/or the amplitude (F3, A3) of the compare signal (S3) in order to derive a first value of a measurement phase displacement (SFR1 ) and/or a first value of a measurement attenuation (AR1 );

- compare the phase and/or the amplitude (F2’, A2’) of the disturbed reference signal (S2’) with the phase and/or the amplitude (F3, A3) of the compare signal (S3) in order to derive a first value of a reference phase displacement (SFF1 ) and/or a first value of a reference attenuation (AF1 );

- derive the value of the moisture content based on the ratio between the first value of the measurement phase displacement (SFR1 ) and the first value of the reference phase displacement (SFF1 ) and/or based on the ratio between the first value of the measurement attenuation (AR1 ) and the first value of the reference attenuation (AF1 ).

A5. The device (1 ) according to paragraph A4, wherein the control unit (4) is programmed to:

- capture a no-load measurement signal (S1 ”) in the absence of material in the measurement space region (R1 );

- derive a second value of the measurement phase displacement (SFR2) and/or a second value of the measurement attenuation (AR2), based on the no-load measurement signal (S1 ”);

- capture a no-load reference signal (S2”) in the absence of material in the measurement space region (R1 ) and derive a second value of the reference phase displacement (SFF2) and/or a second value of the reference attenuation (AF2), based on the no-load reference signal;

- derive the value of the moisture content based on the ratio between the second value of the measurement phase displacement (SFR2) and the second value of the reference phase displacement (SFF2) and/or based on the ratio between the second value of the measurement attenuation (AR2) and the second value of the reference attenuation (AF2).

A6. The device (1 ) according to any one of the preceding paragraphs, comprising a first deviator switch (32), movable between a measuring position (PR1), where the generator (2) is connected to the measuring line (33), and a reference position (PF1 ), where the generator (2) is connected to the reference line (34), and wherein the control unit (4) is programmed to switch the first deviator switch element (32) to the measuring position (PR1 ) to receive the measurement signal (S1), and to switch the first deviator switch element (32) to the reference position (PF1 ) to receive the reference signal (S2).

A7. The device (1 ) according to paragraph A6, comprising a second deviator switch (35), located downstream of the measuring line (33) and of the reference line (34) along the electric circuit and movable between a respective measuring position (PR2), where the control unit (4) is connected to the measuring line (33), and a respective reference position (PF2), where the control unit (4) is connected to the reference line (34), and wherein the control unit (4) is programmed to switch the second deviator switch element (35) to the measuring position (PR2) to receive the disturbed measurement signal (ST), and to switch the second deviator switch element (35) to the reference position (PF2) to receive the disturbed reference signal (S2’), wherein the measuring unit (3) includes a first connector (31 ) and a second connector (36), configured to connect the generator (2) or the control unit (4) to the measuring line (33) and to the reference line (34), wherein the measuring unit (3) is symmetrical and wherein the generator (2) and the control unit (4) can be connected alternatively to the first or the second connector (31 , 36) arbitrarily.

A8. The device (1 ) according to any one of the preceding paragraphs, wherein the measuring line (33) includes:

- a signal electrode (33A), having a flat shape and confronting the measurement space region (R1 );

- a ground electrode (33B), spaced from the signal electrode (33A) and partly surrounding the signal electrode (33A), the signal electrode (33A) being operatively interposed between the ground electrode (33B) and the measurement space region (R1).

A9. The device (1 ) according to paragraph A8, wherein the signal electrode (33A) has a width of between 0.1 cm and 100 cm and wherein the ratio between the width of the signal electrode (33A) and the gap between the signal electrode (33A) and the ground electrode (33B) is between 10 and 2.

A10. The device (1 ) according to paragraph A8 or A9, comprising:

- a first wall (52), including a measuring surface (521 ), associated with the measuring line (33) and operatively confronting the measurement space region (R1), and a supporting surface (522);

- a second wall (53), on which the reference line (34) is disposed;

- a screening wall (54), interposed between the first and the second wall (52, 53) and including a conductive element defining the ground electrode (33B), wherein the signal electrode (33A) is spaced from the conductive element by a dielectric material.

A11. The device (1 ) according to paragraph A10, wherein the screening wall (54) defines a screening tank that includes:

- a conductive coat, defining the ground electrode (33B);

- an insulating cavity (CV), confronting the first wall (52) so that the signal electrode (33A) is spaced from the conductive coat of the screening tank;

- an abutting portion (541 A) is in contact with the supporting surface (522) of the first wall (52).

A12. The device according to any one of the preceding paragraphs, wherein, in the measurement space region (R1 ), the material (M) is spaced from the measuring line (33).

A13. A method for remotely measuring a value of moisture content of a material (M) positioned in a measurement space region (R1 ), comprising the following steps:

- generating a high-frequency electrical measurement signal (S1) by means of a generator (2); - transmitting the measurement signal (S1) to a measuring line (33) which confronts the measurement space region (R1 );

- in response to the measurement signal (S1), generating an electromagnetic field that propagates into the measurement space region (R1);

- disturbing the measurement signal (S1) in response to an interaction of the electromagnetic field with the material disposed in the measurement space region (R1 );

- receiving the disturbed measurement signal (S1 ’) in a control unit (4);

- deriving the value of the moisture content, in the control unit (4), based on the disturbed measurement signal (S1 ’), the method being characterized in that it comprises the following steps:

- generating a high-frequency electrical reference signal (S2) by means of the generator (2);

- transmitting the reference signal (S2) to a reference line (34) that confronts a reference space region (R2) different from the measurement space region (R1 );

- in response to the reference signal (S2), generating an electromagnetic field that propagates into the reference space region (R2);

- receiving the disturbed reference signal (S2’) in a control unit (4);

- deriving the value of moisture content, in the control unit (4), based also on the disturbed reference signal (S2’).

A14. The method according to paragraph A13, wherein the generator (2) generates the measurement signal (S1) and the reference signal (S2) at a predetermined frequency and wherein the control unit (4) perform a pair of capture operations, including one to capture the measurement signal (S1) and one to capture the reference signal (S2).

A15. The method according to paragraph A14, wherein the generator (2) generates the measurement signal (S1) and the reference signal (S2) at a plurality of frequencies and wherein the control unit (4) performs a plurality of pairs of capture operations, each corresponding to one frequency of the plurality of frequencies.

A16. The method according to any one of paragraphs from A13 to A15, wherein the material (M) is spaced, in the measurement space region (R1), from the measuring line (33), to perform a contactless moisture measurement of the material (M).