Feeding assembly

Abstract

Feeding assembly (9) for feeding a ceramic powder material (CP); the feeding assembly comprises: at least one duct (DU), which has an inner passage (LU) for the transit of the powder material (CP) and has at least one wall (W) provided with at least one stretch (ST) made of a material with a porosity ranging from about 10% to about 50% by volume, relative to the total volume of the stretch (ST); and a pressure assembly (PP) for feeding a gas at a relative pressure ranging from about 5 mbar to about 30 mbar to an outer surface (ES) of the stretch (ST) so that at least a part of the gas moves through the stretch (ST) and reaches the passage (LU).

Description

[0001] "FEEDING ASSEMBLY"

[0002] Cross-Reference to Related Applications

[0003] This Patent Application claims priority from Italian Patent Application No. 102024000013060 filed on June 6, 2024, the entire disclosure of which is incorporated herein by reference.

[0004] Technical Field

[0005] The present invention relates to a feeding assembly, a compaction machine and a plant for manufacturing ceramic articles. The present invention also relates to a feeding process, a compaction method and a manufacturing process.

[0006] Background of the Invention

[0007] In the field of ceramic article production (in particular, slabs; more specifically, tiles) , the use of machines for compacting semi-dry powder (ceramic powders; moisture content about 5-6%) is known. These machines comprise ceramic powder feeding devices of different types.

[0008] These machines are often used to manufacture products that imitate natural stones, such as marble and / or granite.

[0009] These products have inner veins distributed randomly or according to predetermined patters within the thickness of the products.

[0010] Alternatively or in addition, it may be appropriate to use powders of different types to obtain articles with particular structural and / or physical characteristics.

[0011] In some cases, powder mixtures of different colours are brought with a random or desired distribution into cavities of steel moulds and then compressed so as to obtain, for example, compacted powder slabs. It has been proposed to produce slabs with distribution of powders of di f ferent colours also using continuous compaction machines comprising a conveyor assembly for conveying ( substantially continuously) the powder material along a given path through a work station, at which a compaction device is arranged, which is adapted, by means of the cooperation of pressure rollers , to compact the powder material so as to obtain a layer of compacted powder .

[0012] An example of a continuous machine for compacting ceramic powder is described in the international patent application with publication number W02005 / 068146 of the same Applicant as the present application .

[0013] It is also known to make ( for example by digital printing) a graphic decoration over the layer of compacted ceramic powder in order to make the finished article visually more similar to a natural product .

[0014] International patent application W02018 / 163124 of the same Applicant discloses a plant for manufacturing ceramic articles comprising two feeding devices , each of which is adapted to contain a powder material of a respective type and feed said powder material to a conveyor assembly; the plant also comprises an operating device , which is adapted to allow the powder material to get out selectively from zones of the feeding devices arranged in succession transversely to the conveying direction, and a control unit that controls the operating device according to a desired reference distribution and how far the conveyor assembly advances the powder material . In particular, the operating device comprises a plurality of operating units each of which is arranged at a respective zone to adj ust the passage of the material through the same zone .

[0015] International patent application WO2023 / 233317 of the same Applicant describes a feeding assembly with at least two feeding devices , each of which is configured to contain a powder material of a respective type and feed the powder material to a conveyor assembly . The feeding assembly comprises an operating device , which is configured to allow the powder material to selectively get out through a first and a second passage zone of the feeding devices arranged in succession, vertically and independently moving a plurality of trans fer sliders by means of operating units .

[0016] CN215395933U relates to a material distribution mechanism for a ceramic production process . The distribution mechanism has a piping and air pas sage holes arranged in the material distribution module . When the compressed air enters the material distribution cavity through the piping and the holes , the flow rate of the compressed air exiting the holes is greater than the flow rate of the compressed air entering the air pressure holes .

[0017] WO2021255548A1 discloses a machine for the dry decoration of ceramic slabs or tiles , comprising : a deposition surface ; a distribution unit , arranged to dispense , in a controlled manner, a ceramic compound in granules or powder, formed by two or more di f ferent ceramic materials ; a storage container, interposed between the distribution unit and the deposition surface to store a certain quantity of ceramic compound dispensed by the distribution unit , and comprising a discharge opening arranged to allow the deposition o f the ceramic compound on the deposition surface . The storage container and the deposition plane are in relative movement with respect to each other along a longitudinal direction . A control module , connected to the distribution unit , is arranged to control and adj ust the delivery of the ceramic compound of the distribution unit . The machine comprises one or more sensors , connected to the control module and arranged to detect a signi ficant parameter of the amount of ceramic compound contained in the storage container and to process a corresponding measurement signal . The control module is arranged to adj ust the delivery of the ceramic compound according to the measurement signal received, so as to maintain a desired amount of ceramic compound inside the container .

[0018] W02020 / 250060 describes a distribution device for distributing a granular material , comprising a distribution channel provided with an inlet opening and an outlet opening . The delivery channel comprises an intermediate portion, which connects the inlet and outlet openings and is provided with a longitudinal axis ; the intermediate portion has a length and a height , measured on a vertical plane containing the longitudinal axis , where the height is measured perpendicularly to the length . The intermediate portion is configured to allow deposition and accumulation of a predetermined amount of granular material from the inlet opening . Motor means are provided that can be activated on command to make the granular material flow forward from the intermediate portion towards the outlet opening .

[0019] However, the plants available so far for manufacturing ceramic articles have several drawbacks .

[0020] Among these we point out the fact that the powder material can create clogs inside the feeding assemblies and / or the products obtained can present unwanted distortions of the distribution of the di f ferent types of powder in the thickness .

[0021] It is noted that in the first case, it is necessary to interrupt the operation of the plant to allow an operator to carry out the necessary maintenance (with a consequent increase in production times and costs ) .

[0022] In the second case , the aesthetics of the products can be altered uncontrollably and, therefore , often pe j oratively .

[0023] Aim of the present invention is to provide a feeding assembly, a compaction machine , a plant for manufacturing ceramic articles , a feeding process , a compaction method and a manufacturing process , which allow to overcome , at least partially, the drawbacks of the prior art and are , at the same time , easy and economical to manufacture .

[0024] Summary

[0025] According to the present invention there are provided a feeding assembly, a compaction machine , a plant for manufacturing ceramic articles , a feeding process , a compaction method and a manufacturing process as claimed in the following independent claims and, preferably, in any one of the claims directly or indirectly dependent on the independent claims .

[0026] Brief Description of the Drawings

[0027] The invention wi ll now be described with reference to the accompanying drawings , which show some non-limiting examples of embodiments , in which :

[0028] - Figure 1 is a side and schematic view of a plant in accordance with the present invention;

[0029] - Figures 2 and 3 are side views of an inner part of the plant of Figure 1 in two di f ferent operating configurations ;

[0030] - Figure 4 is a perspective view of a component of Figures 2 and 3 ;

[0031] - Figure 5 is a perspective view including the part of Figures 2 and 3 ;

[0032] - Figure 6 is a perspective view with some components removed for the sake of clarity of a portion of Figures 2 and 3 ;

[0033] - Figure 7 is a perspective and schematic view of a part of the plant of Figure 1 ;

[0034] - Figure 8 is a virtual representation of a part of the plant control procedure of Figure 1 ;

[0035] - Figures 9 to 12 are side views of an embodiment of the part depicted in Figures 2 and 3 in di f ferent operating configurations ;

[0036] - Figure 13 is a side view of the part of Figures 9 to 12 with the addition of a group of components ; and

[0037] - Figure 14 is a section in enlarged scale of a detail of the embodiment of Figures 9 to 13 .

[0038] Detailed Description

[0039] In Figure 1 , 1 denotes as a whole a plant ( subj ectmatter of a first aspect of the present invention) for manufacturing ceramic articles T .

[0040] The plant 1 is provided with a compaction machine 2 ( in itsel f , independently of other components of the plant 1 , sub ect-matter of a second aspect of the present invention) for compacting powder material CP . In particular, the powder material CP comprises ( is ) ceramic powder . More in particular, the powder material CP consists of particles mainly (i.e., for at least 50% by weight, relative to the overall weight of the powder material CP) with dimensions (diameters) smaller than about 600 m (in particular smaller than about 500 pm) .

[0041] Alternatively or additionally, the powder material CP consists of particles mainly (i.e., for at least 50% by weight, relative to the total weight of the powder material CP) with dimensions (diameters) larger than about 50 pm (in particular, larger than about 90 pm) .

[0042] Advantageously but not necessarily, the powder material CP comprises at least about 70% (in particular, at least about 80%; more in particular, at least 90%) by weight, relative to the total weight of the powder material CP, particles with dimensions smaller than about 600 pm (in particular, smaller than about 500 pm) .

[0043] Advantageously but not necessarily, the powder material CP comprises at least about 70% (in particular, at least about 80%; more in particular, at least 90%) by weight, relative to the total weight of the powder material CP, of particles with dimensions larger than about 50 pm (in particular, larger than about 90 pm) .

[0044] In particular, the powder material CP comprises at least about 70% (in particular, at least about 80%; more in particular, at least 90%) by weight, relative to the total weight of the powder material, particles with dimensions larger than about 100 pm (in particular, larger than about 125 pm) .

[0045] The dimensions are obtained by means of successive sieving with sieves with holes of decreasing dimensions (diameters) . The diameter of the holes of the first sieve that does not allow the passage of particles indicates the dimensions (i.e. diameter) of the particles.

[0046] Measurements by means of successive sieving are carried out as long as the dimensions (i.e. diameters) of the particles and sieve holes allow them (in particular, up to a minimum of 0.05 mm) . Below these dimensions (in particular, 0.05 mm) , the dimensions of the particles are measured (in particular, as mean diameter D(v,0.5) or, alternatively, as distribution) using a laser granulometer - in particular, using a Mastersizer Microplus Ver.2.19 laser granulometer (Malvern Instruments® Ltd) .

[0047] According to some non-limiting embodiments, the powder material CP (in particular, the ceramic powder) has a moisture content of about 5-6%.

[0048] In particular, the ceramic articles T produced are slabs (more precisely, tiles) .

[0049] The machine 2 comprises a compaction device 3, which is arranged at a work station 4 and is adapted to (configured to) compact the powder material CP so as to obtain a layer of compacted powder KP; and a conveyor assembly 5 (configured) to transport (substantially continuously) the powder material CP along a stretch PA of a given path from an input station 6 towards (in particular, to) the work station 4 in an conveying direction A (in particular, substantially horizontal) and the layer of compacted powder KP from the work station 4 along a stretch PB of the given path to an output station 7 (in particular, in the direction A) . In particular, the given path consists of the stretches PA and PB . According to non-limiting embodiments, the compaction device 3 is configured to exert a pressure of at least about 350 kg / cm2(in particular, at least about 380 kg / cm2; in particular, up to (i.e., less than or equal to) about 450 kg / cm2; more in particular, up to about 420 kg / cm2) on the powder material CP.

[0050] In order to avoid misunderstandings, although the matter is already clear, in the present text the expression "up to" referred to a numerical value is equivalent to "less than or equal"; similarly the expression "at least" referred to a numerical value is equivalent to "greater than or equal" .

[0051] In particular, the compaction device 3 is configured to exert on (on a layer of) the powder material CP a pressure transverse (in particular, normal) to the direction A (and to an extension direction DD - defined below in more detail) .

[0052] Advantageously but not necessarily, the compaction device 3 is configured to operate in a continuous manner. In particular, the (layer of) powder material CP is compacted during its continuous advancement.

[0053] Alternatively (according to some non-limiting embodiments not shown) , the compaction device 3 is a discontinuous compaction device (commonly known as a press) . In detail, in this case, when the compaction takes place by means of a discontinuous compaction device, a determined quantity of powder material CP is fed, in use, to a seat of determined shape (typically rectangular or square - more precisely, of the shape of which the compacted ceramic article is to be obtained) of the compaction device 3. At this point, a pressure is exerted on the powder material CP arranged in the seat (and therefore not moving in direction A) so as to obtain the layer of compacted powder KP .

[0054] In particular, in this case, the layer of compacted powder KP substantially has the dimensions of the compacted ceramic article (i.e. the dimensions of a ceramic slab or tile) and even more in particular it is not necessary to cut the layer of compacted powder KP to obtain slabs 48 (described in more detail below) .

[0055] With particular reference to Figures 2, 3, 5, 6, and 9- 14, the machine 2 is also provided with a feeding assembly 9 (per se, independently of other components of the plant 1, subject-matter of a third aspect of the present invention) for feeding the powder material CP.

[0056] With particular reference to Figure 14, the feeding assembly 9 comprises at least one duct DU, which has an inner passage LU for the transit of the powder material CP and has at least one wall W provided with at least one stretch ST made of a material with a (total open) porosity ranging from about 10% to about 50% (in particular, up to about 28%) by volume, relative to the total volume of the stretch ST itself .

[0057] The (total open) porosity is measured with mercury porosimetry according to the provisions of ISO 15901-1:2016 standard. In particular, the porosity is measured with a Pascal 140 / 240 Thermo Fisher Scientific Porosimeter (following the instructions attached to it) . The principles and operation of the mercury porosimetry are well known and are for example described in: Mercury Porosimetry : a General (Practical) Overview, Part. Part. Syst. Charact . 23 (2006) 1-11, Herbert Giesche, DOI: 10.1002 / ppsc .200601009; Characterization of Porous Solids and Powders : Surface Area, Pore Size and Density, S. Lowell, Joan E. Shields, Martin A. Thomas and Matthias Thommes, Kluwer Academic Publishers 2004, ISBN 1-4020-2302-2 (HB) , ISBN 1-4020-2302-0 (e-book) .

[0058] The (total open) porosity is the porosity measured considering the open pores (and not the closed pores) , i.e. the pores that are accessible by a fluid (ISO 15901-1:2016) .

[0059] In particular, the stretch ST comprises (in particular, is made of) an at least partially porous resin.

[0060] The stretch ST has an inner surface IS at least partially delimiting said passage LU and an outer surface ES opposite the inner surface IS and at least partially externally delimiting the duct DU.

[0061] The feeding assembly 9 comprises a pressure assembly PP for feeding a gas (in particular air) under pressure to the outer surface ES so that at least part of the gas flows through the stretch DU and reaches said passage LU.

[0062] The pressure assembly PP is configured to feed the gas (to the outer surface ES) at a relative pressure (the pressure of a system above atmospheric pressure) ranging from about 5 mbar to about 1000 mbar (in particular, at about 95 mbar; more in particular, at about 50 mbar; even more in particular, at about 30 mbar) . In particular, the relative pressure is measured by means of a differential pressure gauge with a column of liquid (water) , where each mbar corresponds to about 10 mm of water column difference. Alternatively, the gas is supplied by controlling the flow rate thereof to avoid possible variations in the pressure loss between the various zones of the machine.

[0063] The pressure is measured immediately upstream of the outer surface ES . In particular, the pressure is measured at the intersection between the conduit CD and the feeding chamber FC (described in more detail below) .

[0064] It has been observed experimentally that, in this way, it is surprisingly possible to reduce the risk of clogging inside the duct DU and / or that the distribution of the particles in the powder material CP is modified. It has been hypothesized that this is due to the fact that, in this way, a sort of gas layer is created on the inner surface IS and therefore the particles of the powder material CP, sliding over it, have less tendency to stop and adhere to the wall W.

[0065] Advantageously but not necessarily, the pressure assembly PP is configured to feed the gas (to the outer surface ES) with a flow rate ranging from about 0.05 L / min.cm2(in particular, from about 0.1 L / min.cm2) to about 0.6 L / min.cm2(in particular, at about 0.4 L / min.cm2) (the flow rate is indicated as the volume of gas over time relative to the extension - to the surface - of the outer surface ES) .

[0066] In particular, the flow rate is measured by a flow rate controller. More in particular, the flow rate controller belongs to the family of speed meter controllers; even more in particular, the flow rate controller is a meter with a calibrated orifice (or diaphragm) , generally referred to in as the "Primary Flow Element". For example, the flow rate controller is IN502-44 from SMC Corporation, Akihabara UDX 15F, 4-14-1, Sotokanda, Chiyoda-ku, Tokyo 101-0021, Japan.

[0067] More in particular, the flow rate is measured immediately upstream of the outer surface ES . In particular, the flow rate is measured at the intersection between the conduit CD and the feeding chamber FC (described in more detail below) .

[0068] In particular, the stretch ST has at least one lateral edge LE that joins (connects) the outer surface ES and the inner surface IS.

[0069] Advantageously but not necessarily, the stretch ST has (in section) a shape substantially tapered (it is substantially tapered) from the outer surface ES towards (to) the inner surface IS (towards the passage LU) . In other words, in particular, the inner surface IS has a smaller extension than the outer surface ES .

[0070] It has been experimentally observed that, in this way, the risk that the stretch ST moves and / or that preferential gas passages (in particular air) are created along the lateral edge LE of the stretch ST is surprisingly reduced.

[0071] Advantageously but not necessarily, the wall W has (in section) a seat H substantially tapered (from the outside) towards the passage L. In particular, the seat H has an inner surface having a shape complementary to that of the lateral edge LE .

[0072] Also in this case, it has been experimentally observed that, in this way, the risk that the stretch ST moves and / or that preferential gas passages (in particular air) are created along the lateral edge LE of the stretch ST is surprisingly reduced.

[0073] Advantageously but not necessarily, the stretch ST is surf ace-treated (e.g. by means of a paint) so that a surface part thereof is impermeable ( f luid-tight ) . In particular, the lateral edge LE has a surface treatment (so as to be) (at least partially) impermeable ( f luid-tight ) . It has been experimentally observed that , in this way, the risk of preferential gas pas sages ( in particular air ) being created along the lateral edge LE of the stretch ST is surprisingly reduced .

[0074] More in particular, the outer surface ES and the inner surface IS are free ( or are at least for the most part free ) . In addition or alternatively, the surface treatment substantially covers the entire lateral edge LE .

[0075] According to some non-limiting embodiments , the pressure assembly PP comprises a pressure source PS ( for example , a pump - schematically represented in Figure 14 ) and at least one conduit CD, which connects the pressure source PS to the stretch ST ( in particular, to its outer surface ES ) .

[0076] In Figure 14 , the arrows represent the direction of gas supply .

[0077] According to some non-limiting embodiments , the pressure assembly PP comprises a feeding chamber FC, which is arranged between the conduit CD and the stretch ST ( directly in connection with the stretch ST - nothing is interposed between the feeding chamber FC and the stretch ST ) and covers at least a maj ority portion of the outer surface ES . In particular, the feeding chamber FC has a section ( cross-section - perpendicular to the gas feeding direction) at least double ( in particular, at least triple ; more in particular, no more than quadruple ) of the section ( cross-section - perpendicular to the gas feeding direction) of the conduit CD ( at its insertion into the feeding chamber FC ) .

[0078] Advantageously but not necessarily, the stretch ST has a thickness of up to (less than or equal to) about 30 mm (in particular, up to 20 mm) . Alternatively or in addition, the stretch ST has a thickness of at least (greater than or equal to) 3 mm.

[0079] Advantageously but not necessarily, the stretch ST has pores with a median diameter ranging from about 0.5 pm (in particular, from about 5 pm) to about 80 pm (in particular, to about 15 pm) .

[0080] Unless otherwise specified, in the present text, by diameter of a pore it is meant the limiting diameter, i.e. the diameter of a circle having the same area of the smaller (cross) section of the pore.

[0081] The median diameter of the pores is measured with mercury porosimetry, in particular with a Pascal 140 / 240 Thermo Fisher Scientific Porosimeter (following the instructions attached to it) . The principles and operation of mercury porosimetry are well known (see the documents mentioned above in this regard) . In particular, the median diameter of the pores is measured according to the provisions of ISO 15901-1:2016 standard.

[0082] Note that by median diameter is meant the diameter corresponding to the fiftieth percentile of the pore volume, i.e. the diameter for which half of the pore volume is in the largest pores and half of the pore volume is in the smallest pores (ISO 15901-1:2016, in particular paragraph 3.16) .

[0083] Advantageously but not necessarily, the stretch ST (in particular, the mentioned resin) has an elastic modulus under flexion (measured according to the provisions of DIN 53457 standard) ranging from about 440 MPa to about 2100 MPa. Advantageously but not necessarily, the stretch ST ( in particular, the mentioned resin) has a tensi le elastic modulus (measured according to the provisions of DIN 53457 standard) ranging from about 570 MPa to about 2100 MPa .

[0084] Advantageously but not necessarily, the stretch ST ( in particular, the mentioned resin) has a compressive breaking load (measured according to the provisions of DIN 53454 standard) ranging from about 11 MPa to about 130 MPa .

[0085] Advantageously but not necessarily, the stretch ST ( in particular, the mentioned resin) has a compression elastic modulus (measured according to the provisions of DIN 53457 standard) ranging from about 300 MPa to about 1700 MPa .

[0086] According to some embodiments , the stretch ST ( in particular, the mentioned resin) has a total open porosity as indicated above . In addition or alternatively, the stretch ST ( in particular , the mentioned resin) has a breaking load under flexion as indicated above . In addition or alternatively, the stretch ST ( in particular, the mentioned resin) has a tensile breaking load as indicated above . In addition or alternatively, the stretch ST ( in particular, the mentioned resin) has pores with a median diameter as indicated above .

[0087] Advantageously but not necessarily, the duct DU has a width ranging from about 10 mm ( in particular, from about 15 mm) to about 10 cm ( in particular, to about 4 cm) at said stretch .

[0088] Although it has been observed that obstructions in ducts of these dimensions occur in particular often and are in particular di f ficult to unblock, the present invention has experimentally demonstrated to solve these problems . Advantageously but not necessarily, the stretch ST has a length of at least 2 cm ( in particular, at least 3 cm; more in particular, at least 4 cm) . In addition or alternatively, the stretch ST has a length of up to about 60 cm ( in particular, up to about 40 cm; in particular, up to about 20 cm) .

[0089] It has been experimentally observed that , surprisingly, a relatively short length is suf ficient to obtain the advantages indicated above .

[0090] According to some non-limiting embodiments , the feeding assembly 9 comprises a feeding device 10 and at least one feeding device 11 ( in particular, arranged above the conveyor assembly 5 ) . The feeding device 10 comprises a respective containing chamber 12 having at least one relative output mouth 13 . The second feeding device 11 comprises at least one respective containing chamber 14 having a relative output mouth 15 , the longitudinal extension of which is parallel to the longitudinal extension of the output mouth 13 .

[0091] In particular, the longitudinal extension of the output mouths 13 and 15 are transverse ( in particular, substantially perpendicular ) to the conveying direction A ( this longitudinal extension is , in particular, substantially hori zontal ) . In other words , the output mouth 13 and the output mouth 15 extend in an extension direction DD transverse ( in particular, substantially perpendicular - see Figures 5 and 6 ) to the conveying direction A ( such extension direction DD is , in particular, substantially hori zontal ) .

[0092] Advantageously but not necessarily, the duct DU is a part of the containing chamber 12 at the output mouth 13 and / or of the containing chamber 14 at the output mouth 15 . More precisely but not necessarily, the containing chamber 12 is adapted to (configured to) contain a (ceramic) powder material CA of a first type and the containing chamber 14 is adapted to (configured to) contain a (ceramic) powder material CB of a second type.

[0093] According to some non-limiting embodiments, the powder materials CA and CB (are ceramic and) have colours different from one another. In this way it is possible to create chromatic effects in the thickness of the ceramic articles T. Such chromatic effects are for example visible in the edges of the ceramic articles. Alternatively or in addition, the powder materials CA and CB are adapted to (configured to) bring different physical characteristics to the ceramic articles T.

[0094] In particular, the powder material CP consists of one or both of the powder materials CA and CB . More precisely, the powder material CP comprises (consists of) the powder materials CA and CB (distributed in mutually different zones of the powder material CP) .

[0095] According to some non-limiting embodiments (such as those shown in Figures 2, 3, 5 and 6) , the feeding device 10 comprises a (single) containing chamber 12 while the feeding device 11 comprises two containing chambers 14 and 14' (arranged on opposite sides of the containing chamber 12) . Moreover, each containing chamber 14 and 14' has a respective output mouth 15 and 15' (in particular, substantially facing each other) .

[0096] According to some non-limiting embodiments, the output mouth 13 has respective passage zones 16 (see, in particular, Figures 5 and 6) arranged in succession along the longitudinal extension of the output mouth 13 itself. The output mouth 15 (and the output mouth 15' ) has respective passage zones 17 arranged in succession along the longitudinal extension of the output mouth 15 itself. The feeding assembly 9 further comprises an operating device 18 (see, in particular, Figures 2 and 3) , which is adapted to (configured to) allow the powder material to get out selectively through one or more of the passage zones 16 and 17. In particular, each passage zone 16 is arranged next to (more precisely, above; in particular, associated with) a respective passage zone 17.

[0097] Advantageously but not necessarily, the machine 1 further comprises (Figure 1) a control unit 20, which is adapted to (configured to) store (has stored) a reference distribution 21 (Figure 8) of the powder material CA and CB of the first and second type (to be obtained) in the powder material CP transported by the conveyor assembly 5 and to control the operating device 18 as a function of the reference distribution 21. More in particular, the control unit 20 is adapted to (configured to) control the operating device 18 so as to reproduce (on the conveyor assembly 5) the reference distribution 21.

[0098] According to some non-limiting embodiments (see, in particular, Figure 1) , the machine 1 also comprises a detection device 19 (for example an encoder) for detecting how long the conveyor assembly 5 transports the powder material CP along the given path (in the conveying direction A) , in particular, along the stretch PA. In these cases, in particular, the control unit 20 is adapted to (configured to) control the operating device 18 as a function of what is detected by the detection device 19 and the reference distribution 21. More in particular, the control unit 20 is adapted to (configured to) control the operating device 18 as a function of what is detected by the detection device 19 so as to reproduce (on the conveyor assembly 5) the reference distribution 21.

[0099] According to some non-limiting embodiments (see, in particular, Figures 5, 6 and 11-13) , the operating device 18 comprises a plurality of operating units 22 (only four of which partially shown in Figures 5 and 6; eight shown in Figures 11-13) , each of which is adapted to (configured to) adjust the passage of the powder material through a respective passage zone 16 and 17.

[0100] In particular, each operating unit 22 is arranged at a respective passage zone 16 and 17.

[0101] Advantageously but not necessarily (see, in particular, Figures 2-6 and 9-13) , each operating unit 22 comprises a respective transfer slider 23 (an embodiment of which is shown in more detail in Figure 4) , which has a transit channel 24 (i.e. a hollowed-out corridor or conduit) provided with at least one input 25 and at least one output 26 arranged under the input 25, and a respective actuator 27 (Figure 13) to move the transfer slider 23 to a first position FP, in which the transit channel 24 is connected to the containing chamber 12 (Figures 3 and 9) so that the powder material CA of the first type moves from the containing chamber 12 to the transit channel 24, and at least to a second position SP, which is arranged below the first position FP and in which the transit channel 24 is connected to the containing chamber 14 (and / or 14' ) (Figures 2 and 11) so that the powder material CB of the second type moves from the containing chamber 14 ( and / or 14 ' ) to the transit channel 24 .

[0102] According to some non-limiting embodiments , the operating units 22 are arranged in succession ( in a direction transverse to the conveying direction A) along the longitudinal extension of the output mouth 13 and the output mouth 15 . More precisely but not necessarily, each slider 23 ( described in more detail below) of the operating units 22 is arranged at a respective passage zone 16 and 17 .

[0103] In particular, the sliders 23 are arranged in succession ( in particular, in line ) in the extension direction DD ( in particular, substantially hori zontal ) .

[0104] Advantageously but not necessarily, the control unit 20 is configured to control each operating unit 22 independently of the other operating units 22 ( depending on what is detected by the detection device 19 and the reference distribution 21 ) .

[0105] In particular, in use , the control unit 20 advances (virtually) the reference distribution 21 along a virtual path VP ( Figure 8 ) through a virtual reference front RP as a function of ( according to ) what is detected by the detection device 19 . The virtual reference front VP has a plurality of positions , each of which corresponds to a passage zone 16 and a passage zone 17 associated with each other ; the control unit 20 operates the feeding assembly 9 ( in particular, the feeding devices 10 and 11 ; more in particular, the operating device 18 ; even more in particular, the operating units 22 ) so as to allow the powder material to get out at a speci fic time through the passage zones 16 and / or 17 depending on the type of powder material provided at the specific time, in the reference distribution 21, in the positions of the virtual reference front RP corresponding to said passage zones 16 and / or 17.

[0106] In still other words, each actuator 27 is configured to move (in particular, substantially vertically) the slider 23 (at least) from the first position FP to the second position SP and vice versa.

[0107] According to some non-limiting embodiments, each operating unit 22 is configured so that, when the transfer slider 23 is in the first position FP, the slider 23 clogs (at least partially; more in particular, completely) the output mouth 13.

[0108] In addition or alternatively, each operating unit 22 is configured so that, when the transfer slider 23 is in the first position FP, the slider 23 clogs (at least partially; more in particular, completely) the output mouth 13.

[0109] With particular reference to Figure 4, advantageously but not necessarily, each transit channel 24 is provided with at least one further input 28. According to some nonlimiting embodiments (see for example Figures 3 and 9) , in the first position FP, the input 28 is connected to the containing chamber 12 so that the powder material CA of the first type moves from the containing chamber 12 to the transit channel 24 (through the input 28) .

[0110] Advantageously but not necessarily, (when the transfer slider 23 is) in the second position SP (Figure 2) , the input 28 is arranged so that the powder material CB of the second type moves (from the feeding device 11) to the channel 24 (also) through the input 28. More in particular, when the transfer slider 23 is in the second position SP, the input 28 is arranged in such a way that it is connected to the further containing chamber 14 ' ( of the feeding device 11 and; more in particular, containing the powder material CB of the second type ) so that the powder material CB of the second type moves from the containing chamber 14 ' to the transit channel 24 ( through the input 28 ) . More in particular, the input 28 faces the further output mouth 15 ' of the containing chamber 14 ' .

[0111] Advantageously but not necessarily, ( each operating unit 22 is configured so that , when the trans fer slider 23 is ) in the second position SB, the powder material CA coming from the feeding device 10 ( in particular, from the containing chamber 12 ) does not enter the transit channel

[0112] 24 .

[0113] According to some non-limiting embodiments , the input

[0114] 25 and the input 28 are arranged on opposite sides of the respective trans fer slider 23 .

[0115] According to some non-limiting embodiments ( see in particular Figure 4 ) , each trans fer slider 23 comprises a respective base wall 32 which partially delimits the transit channel 24 . In particular, each base wall 32 is transverse to a direction of longitudinal extension of the output mouth 13 and, in particular, of the output mouth 15 . More in particular, each base wall 32 is substantially parallel to the conveying direction A.

[0116] Advantageously but not necessarily, each trans fer slider 23 is devoid of a wall opposite the base wal l 32 . In other words , the channel 24 is a recess ( open above ) in the body of the slider 23 , which therefore has at least one portion 34 in relief relative to the channel 24 ( Figure 4 ) . With particular reference to Figures 2, 3 and 9-13, advantageously but not necessarily, each operating unit 22 comprises a respective operating connection 33 (in particular, a respective operating rod 33; in some nonlimiting cases, the operating rod 33 is a wire) , which is connected to the respective slider 23 and to the respective actuator 27 so as to transfer a movement (generated by) from the actuator 27 towards the (in particular, to the) slider 23. According to some non-limiting embodiments, the operating connection (in particular, the rod) 33 extends from the slider 23 (in particular, from an upper end of the slider 23) upwards (in particular, vertically; according to some embodiments, through the containing chamber 12) .

[0117] For example, the actuator 27 comprises a pneumatic drive or an electric motor (in particular, linear) . Advantageously but not necessarily, the actuator 27 is arranged above the containing chamber 12.

[0118] With particular reference to Figures 9 to 12, advantageously but not necessarily, the feeding assembly 9 comprises at least another feeding device 30' , which is arranged above the conveyor assembly 5 (in particular, at the input station 6) and comprises a respective containing chamber 30 configured to contain a powder material of a third type (ceramic material not specifically shown) and having a relative output mouth 29, the longitudinal extension of which is transverse (in particular, perpendicular) to the conveying direction A (such longitudinal extension is, in particular, substantially horizontal) . In particular, the longitudinal extension of the output mouth 29 is substantially parallel to the longitudinal extension of the output mouth 15 ( and optionally of the output mouth 13 ) .

[0119] According to some embodiments , the powder material of the third type has a colour di f ferent from that of the powder materials CA and CB . In particular, the powder material CP consists of one of the powder materials of the three types or ( advantageously) of the powder materials of all three types .

[0120] The output mouth 29 has respective passage zones 31 arranged in succession along the longitudinal extension of the third output mouth 29 itsel f .

[0121] In particular, the operating device 18 is configured to allow ( in particular, and / or prevent ) the powder material of the third type to get out through the passage zones 31 .

[0122] More precisely but not necessari ly, ( each operating unit 22 is configured so that , when the trans fer slider 23 is ) in the third position TP, the input 28 faces the output mouth 29 .

[0123] In particular, the third position TP is between the first position FP and the second position SP .

[0124] Advantageously but not necessarily, each actuator 27 is configured to move the respective slider 23 between the first position FP and the third position TP and between the third position TP and the second position SP in a direction ( in particular, substantially vertical ) transverse ( in particular, substantially perpendicular ) to the direction A.

[0125] Advantageously but not necessarily, ( each operating unit 22 is configured so that , when the trans fer slider 23 is ) in the third position TP, the powder material CA and / or CB coming from the feeding devices 10 and / or 11 ( in particular, from the containing chambers 12 and / or 14 ) does not enter the transit channel 24.

[0126] It should be noted that in these situations, after the slider has blocked the passage of the powder, it is easier for clogs to be created that no longer allow the powder to pass through even when the output mouths 13 and 29 are reopened. The clogs thus created are the most difficult to solve .

[0127] It has been experimentally noted that the present invention has demonstrated to solve these problems.

[0128] According to some non-limiting embodiments (see, in particular, Figures 9-13) , the feeding assembly 9 comprises at least one further (in the present case, fourth) feeding device 10' (structurally and functionally analogous to the feeding device 30' ) , which is arranged above the conveyor assembly 5 (and below the feeding device 30' ) and comprises a respective containing chamber 12' (analogous to the containing chamber 30) configured to contain a powder material of a fourth type (ceramic material not specifically shown) and having a relative (fourth) output mouth 57 (analogous to the output mouth 29) , the longitudinal extension of which is transverse (in particular, perpendicular) to the conveying direction A (such longitudinal extension is, in particular, substantially horizontal) . According to some embodiments, the powder material of the fourth type has a different colour from that of the powder materials CA and CB and of the third type.

[0129] The fourth output mouth 57 has respective fourth passage zones 58 (similar to the passage zones 31) arranged in succession along the longitudinal extension of the fourth output mouth 57 itself. In particular, each fourth passage zone 58 is arranged adj acent (more precisely, between; in particular, associated with) a respective passage zone 31 , a passage zone 17 and a respective passage zone 16 .

[0130] More precisely but not necessarily, each actuator 27 is configured to move the trans fer slider 23 at least to a fourth position FFP, in which the transit channel 24 is connected to the containing chamber 12 ' of the fourth feeding device 10 ' so that the powder material of the fourth type moves to the transit channel 24 ( in particular, through the fourth output mouth) .

[0131] Advantageously but not necessarily, the duct DU is a part of the containing chamber 12 at the output mouth 13 and / or of the containing chamber 14 at the output mouth 15 and / or of the containing chamber 30 at the output mouth 29 and / or of the containing chamber 12 ' at the output mouth 57 .

[0132] Advantageously but not necessarily, ( each operating unit 22 is configured so that , when the trans fer slider 23 is ) in the fourth position FFP, the powder material of the third type and / or CA and / or CB coming from the feeding devices 30 ' and / or 10 and / or 11 ( in particular, from the containing chambers 30 and / or 12 and / or 14 ) does not enter the transit channel 24 .

[0133] Advantageously but not necessarily, the feeding assembly 9 compri ses a trans fer chamber 35, which i s shaped to contain the powder material CP received from the feeding device 10 (more precisely from the containing chamber 12 ) and from the feeding device 11 (more precisely, from the containing chamber 14 ) ( in particular, also from the feeding device 30 ' ; more precisely, from the containing chamber 30 ) , through the channels 24 and to trans fer the powder material CP to the conveyor assembly 5 at the input station 6 .

[0134] Advantageously but not necessarily, the trans fer chamber 35 comprises ( in particular, is ) the duct DU ( as defined above ) extending transversely ( in particular, perpendicularly) to the conveying direction A. In particular, the duct DU comprises a further wall WW arranged facing and upstream of the wall W relative to the conveying direction A.

[0135] In particular, each trans fer slider 23 has a rear side wall 34 ' and a front side wall 34" arranged in succession ( the side wall 34" downstream of the side wall 34 ' ) in the conveying direction A and laterally limiting the respective transit channel 24 . Note that the side walls 34 ' and 34" are part of the portions 34 in relief .

[0136] According to some non-limiting embodiments ( see Figure 4 ) , the slider 23 also has an upper wall 34 * , which delimits the respective transit channel 24 at the top . The upper wall 34 * is part of the portion 34 in relief .

[0137] Advantageously but not necessarily, the compaction machine 2 comprises a plurality of groups 38 of the operating units 22 . Each group 38 comprises at least two operating units 22 contiguous with one another . In other words , the sliders 23 of the same group 38 are arranged in succession ( in particular, seamlessly; more in particular, in contact ) transversely ( in particular, perpendicularly) to the conveying direction A ( in particular, along the longitudinal extensions of the output mouths 13 and 15 ) .

[0138] In particular, the sliders 23 of the same group 38 are arranged in succession ( in particular, seamlessly; more in particular, in contact ) substantially in the extension direction DD .

[0139] Each actuator 27 comprises a movable element 39 , connected ( in particular integral ) to the respective operating connection 33 , and a moving system 39 ' (per se of substantially known type - for example , a linear motor, in particular electric) for moving the movable element 39 in a respective defined direction D . The defined directions D ( of the moving systems ) of the operating units 22 belonging to the same group 38 of the operating units 22 being di f ferent from each other and transversal to each other .

[0140] According to some non-limiting embodiments , the movable element 39 is part of the respective operating connection 33 . In these cases , more precisely but not necessarily, the movable element 39 defines one end of the respective operating connection 33 .

[0141] Advantageously but not necessarily, each group 38 of the operating units 22 comprises at least three ( in particular, at least four ; more in particular, at least six ; even more in particular, at least eight ) operating units 22 ( contiguous with one another ) .

[0142] According to some non-limiting embodiments , the actuators 27 of a same group 38 of the operating units 22 are arranged in succession ( one after the other, in particular in line ) transversely to the extension direction DD of the output mouths 13 and 14 . In particular, the actuators 27 of a same group 38 of the operating units 22 are arranged in succession substantially in the conveying direction A.

[0143] More precisely but not necessarily, the actuators 27 of a same group of the operating units 22 are arranged substantially on the same plane (in particular, transverse to the longitudinal extension direction DD of the output mouths 13, 14; more in particular, substantially in the conveying direction A) .

[0144] Advantageously but not necessarily, each operating connection 33 comprises (in particular, is) at least one flexible operating rod (and, in particular, with reduced deformation memory) .

[0145] According to some non-limiting embodiments, said operating rod is made with (of) metal (in particular with - of- steel) , in particular with high tensile strength.

[0146] In some non-limiting cases, the operating rod (each rod) has a tensile strength Rm greater than 800 MPa (in particular, greater than 1200 MPa; more in particular, greater than 1600 MPa) .

[0147] In addition or alternatively, the operating rod (each rod) has a tensile strength Rm of up to 3000 MPa (in particular, up to 2800 MPa) .

[0148] For example, the rod is made of spring steel C72 UNI 10270-1 and / or 52SiCrNi5 UNI 10270-2 and the like.

[0149] In particular, the tensile strength Rm of the rod is measured in accordance with the provisions of ISO 6892-1:2019 standard (in particular, operating under standard conditions) .

[0150] According to some non-limiting embodiments, said operating rod has a cross-section with an area ranging from 1 to 4 mm2(in particular, with a diameter from 1 to 2 mm) .

[0151] Alternatively and in accordance with embodiments not shown, the operating connection 33 comprises a first rack rod directly connected to a respective actuator 27 adapted to move it ( longitudinally) ; a second rod having a first end ( integrally) connected to a respective slider 23 and a second rack end; and an intermediate kinematic chain configured to trans fer the movement from the first rack rod to the second rack rod and comprising, in particular, a plurality of toothed wheels meshed one another .

[0152] According to other not shown embodiments , the operating connection 33 comprises other types of kinematics .

[0153] Advantageously but not necessarily, each group 38 of the operating units 22 comprises at least two ( in particular, at least four ; more in particular, at least six ; even more in particular, at least eight ) guide channels ( depicted in hatching in Figure 13 ) , inside each of which one of said operating connections 33 ( in particular, the operating rod) extends at least partially and slidably .

[0154] According to some non-limiting embodiments , each guide channel is at least partially curved and has an upper open end and a lower open end, which is at least partially directed downward . More precisely but not necessarily, each lower open end i s arranged above ( in particular, directed towards ) the respective slider 23 ( i . e . of the slider 23 of its own operating unit 22 ) .

[0155] In particular, each guide channel at least partially bends the respective operating connection 33 ( in particular, the operating rod) . More in particular, in use , as each operating connection 33 ( in particular, the operating rod) slides along the respective guide channel it deforms to fit to the shape of the guide channel .

[0156] Advantageously but not necessarily, the lower open ends of the guide channels (of a same group 38 of operating units 22) are arranged substantially transversely in succession (in particular, in transverse line) (in particular, perpendicularly) to the conveying direction A (in particular, they are arranged in succession - more in particular, in line - in the direction DD) .

[0157] According to some non-limiting embodiments, each of said groups 38 of operating units 22 comprises a manifold 43, in which said guide channels are obtained. In particular, each manifold 43 is (substantially) solid (i.e. has no voids) except for the guide channels.

[0158] It should be noted that although the stretch ST and the pressure assembly PP are shown in Figure 10 in the context of the embodiment of Figure 9-13, what has been said above in relation to these aspects (the stretch ST and the pressure assembly PP) is to be understood as also being described for the embodiment of Figures 2-6. In other words, the stretch ST is in some cases positioned in a wall of one or more of the containing chambers 12, 14 and 14' at the output mouths 13, 15 and / or 15' .

[0159] According to some non-limiting embodiments, the plant 1 comprises a printing device 44 (Figure 1) , which is adapted to create a graphic decoration over the layer of (ceramic) compacted powder KP transported by the conveyor assembly 5 and is arranged at a printing station 45 (arranged upstream of the output station 7) along the given path (in particular, along the stretch PB) downstream of the work station 4. The control unit 20 is adapted to control the printing device 44 so as to create a graphic decoration coordinated with said reference distribution 21, in particular so that at the powder material CA ( or CB ) a graphic decoration of a particular colour is ( selectively) made .

[0160] Advantageously but not necessarily, the plant 1 comprises a further application assembly 46 for at least partially covering the layer of powder material CP with a layer of a further powder material . In particular, the application assembly 46 is arranged along the given path (more precisely along the stretch PA) upstream of the work station 4 ( and upstream of the printing station 45 ) .

[0161] In particular, the machine 1 also comprises a cutting assembly 47 for transversely cutting the layer of compacted powder KP so as to obtain slabs 48 , each having a portion of the layer of compacted powder KP . More in particular, the cutting assembly 47 is arranged along the stretch PB of the given path (between the work station 4 and the printing station 39 ) . The slabs 48 compri se ( consist of ) compacted powder KP .

[0162] Advantageously but not necessarily, the cutting assembly 47 comprises at least one cutting blade 49 , which is adapted to come into contact with the layer of compacted powder KP and to cut it crosswise .

[0163] According to some non-limiting embodiments , the cutting assembly 47 also comprises at least two further blades 50 , which are arranged on opposite sides of the stretch PB and are adapted to cut the layer of compacted powder KP and define lateral edges of the slabs 48 ( and substantially parallel to the direction A) - optionally dividing the slab 48 into two or more longitudinal portions . In some speci fic cases , the cutting assembly 47 is as described in the patent application with publication number EP1415780 . In particular, the plant 1 comprises at least one firing kiln 51 for sintering the layer of compacted powder KP of the slabs 48 so as to obtain the ceramic articles T . More in particular, the firing kiln 51 is arranged along the given path (more precisely along the stretch PB ) downstream of the printing station 45 ( and upstream of the output station 7 ) .

[0164] According to some non-limiting embodiments , the plant 1 also comprises a dryer 52 arranged along the stretch PB downstream of the work station 4 and upstream of the printing station 45 .

[0165] According to some non-limiting embodiments , the conveyor assembly 5 comprises a conveyor belt 53 extending ( and adapted to move ) from the input station 6 and through the work station 4 , along the (more precisely, part of ) mentioned given path .

[0166] In some cases , the feeding assembly 9 is adapted to move a layer of powder material CP (not compacted) to ( over ) the conveyor belt 53 ( at the input station 6 ) ; the compaction device 3 is adapted to ( configured to ) exert on the layer of powder material CP a pressure transverse ( in particular, normal ) to the surface of the conveyor belt 53 .

[0167] According to some non-limiting embodiments , a succession of transport rollers is provided downstream of the belt 53 .

[0168] According to some embodiments , in particular, the compaction device 3 comprises compression rollers 54 arranged on oppos ite sides of ( one above and one below) the conveyor belt 53 to exert a pressure on the powder material CP so as to compact the powder material CP itsel f ( and obtain the layer of compacted powder KP ) . Although four rollers 54 are shown in Figure 1 , in accordance with some variants , it is also possible to provide a plurality of rollers 54 arranged above and below the conveyor belt 53 , such as for example described in patent EP1641607B1 , or a structure as described in W02023 / 233317 , from which further details of the compaction device 3 can be derived .

[0169] Advantageously ( as in the embodiment shown in Figure 1 ) but not necessarily, the compaction device 3 comprises a pressure belt 55 , which converges towards the conveyor belt 53 in the conveying direction A. In this way, a pressure ( from top to bottom) is exerted which gradually increases in the direction A on the powder material CP so as to compact it .

[0170] According to some non-limiting embodiments , the conveyor belt 53 is (mainly) made of metal ( steel ) .

[0171] Advantageously but not necessarily (with particular reference to figures 9- 12 ) , the operating device 18 comprises a protection system for the operating units 22 ( in particular, for the operating connections 33 ) ; in particular, the protection system being adapted to reduce the risk ( in particular, to prevent ) that the operating connections 33 ( and the upper part of the sliders 23 ; more precisely but not necessarily, the upper part 34* ) come into contact with the powder material ( e . g . CA and / or CB ) .

[0172] In this way, the operation of each operating unit 22 is improved by reducing the force necessary for the movement ( especially upwards ) of the sliders 23 and the wear of the di f ferent parts .

[0173] More in particular, said protection system comprises two protection walls 59 arranged transversely to the direction A ( in particular, substantially perpendicularly) , on opposite sides of the operating connections 33 , in succession in the direction A. In other words , the walls 59 delimit a sliding channel ( in particular, transverse to the direction A; more in particular, substantially vertical ) for the operating connections 33 and (partially) for the slider 23 ( in particular, for the upper wall 34 * ) .

[0174] According to some non-limiting embodiments , the plant 1 ( the machine 2 and the compaction device 3 ) , except for what is indicated in relation to the duct DU, is as described in the international patent application WO2023 / 233317 of the same Applicant .

[0175] According to a fourth aspect of the present invention, a process for feeding a powder material CP ( in particular comprising ceramic powder and) consisting mainly of particles with dimensions smaller than about 600 m ( in particular smaller than about 500 m) is provided . The process is implemented by a feeding assembly 9 as described above ( in accordance with the third aspect of the present invention) and comprises at least one feeding step during which the powder material moves along the duct DU and ( substantially simultaneously) the pressure assembly PP feeds the gas ( in particular, air ) at a relative pressure ranging from about 5 mbar to about 30 mbar to the outer surface ES so that at least a part of the gas moves through the stretch ST and reaches said passage LU .

[0176] According to some non-limiting embodiments , the process comprises at least one interruption step, during which the powder material CP is stopped inside the duct DU ( in particular, at the stretch ST ) . The feeding step is subsequent to the interruption step .

[0177] It should be noted that even under these conditions , which are in particular prone to lead to the formation of clogs , a surprising reduction in occlusions has been observed thanks to the present invention .

[0178] Advantageously but not necessarily, the powder material CP is as described above .

[0179] In particular, the process comprises a plurality of feeding steps ( each as the above-described feeding step ) and interruption steps ( each as the above-described interruption step ) alternated with one another .

[0180] In accordance with a fi fth aspect of the present invention, a method for compacting a powder material CP ( in particular, comprising ceramic powder ) and consisting of particles mainly with dimensions smaller than about 600 m ( in particular, smaller than about 500 pm) and, in particular, mainly with dimensions larger than about 50 pm ( in particular, larger than about 90 pm) is provided .

[0181] The method comprises a compaction step, during which a conveyor assembly 5 conveys the powder material CP along a first stretch PA of a given path in a conveying direction A from the input station 6 to the work station 4 and a layer of compacted powder KP along a second stretch PB of the given path from the work station 4 to an output station 7 .

[0182] During the compaction step, a compaction device 3 compacts the powder material CP so as to obtain the layer of compacted powder KP .

[0183] Advantageously but not necessarily, the compaction step takes place continuously (not intermittently) . The method further comprising the process for feeding the powder material CP as described above ( in accordance with the fourth aspect of the present invention) .

[0184] Advantageously but not necessarily, the method is implemented by the compaction machine 2 described above ( in accordance with the second aspect of the present invention) .

[0185] In accordance with a sixth aspect of the present invention, a process for manufacturing ceramic articles T is provided; the process comprises : the above-described method ( in accordance with the fi fth aspect of the present invention) ; a cutting step, during which a cutting assembly 47 transversely cuts the layer of compacted powder KP so as to obtain slabs 48 , each having a portion of the layer of compacted powder KP ; and at least one firing step, during which a firing ki ln 51 sinters the layer of compacted powder KP of the slabs 48 so as to obtain ceramic articles T .

[0186] Advantageously but not necessarily, the method is implemented by the plant 1 described above ( in accordance with the first aspect of the present invention) .

[0187] Unless the contrary is explicitly indicated, the content of the references ( articles , books , patent applications , etc . ) cited in this text is referred to in full herein . In particular, the aforementioned references are incorporated herein by reference .

Claims

CLAIMS1. A feeding assembly for feeding a powder material (CP) , which comprises ceramic powder and consists of particles mainly with dimensions smaller than about 600 m (in particular, smaller than about 500 m) and mainly with dimensions larger than about 50 pm (in particular, larger than about 90 pm) ; the feeding assembly (9) comprises at least one duct (DU) , which has an inner passage (LU) for the transit of the powder material (CP) and has at least one wall (W) provided with at least one stretch (ST) made of a material with a porosity ranging from about 10% to about 50% (in particular, up to about 28%) by volume, relative to the total volume of said stretch (ST) ; said stretch (ST) having an inner surface (IS) at least partially delimiting said passage (LU) and an outer surface (ES) opposite the inner surface (IS) and at least partially externally delimiting the duct (DU) ; the feeding assembly (9) comprises a pressure assembly (PP) for feeding a gas under pressure to the outer surface (ES) so that at least part of the gas flows through said stretch (ST) and reaches said passage (LU) ; the pressure assembly (PP) is configured to feed the gas at a relative pressure ranging from about 5 mbar to about 1000 mbar.

2. The feeding assembly according to claim 1, wherein the pressure assembly (PP) is configured to feed the gas at a relative pressure up to about 95 mbar (in particular, up to about 30 mbar) .

3. The feeding assembly according to claim 1 or 2,wherein said stretch (ST) has a thickness up to about 30 mm.

4. The feeding assembly according to any one of the preceding claims, wherein said stretch (ST) has a thickness ranging from about 3 mm to about 15 mm and pores with a mean diameter ranging from about 0.5 (in particular, from about 5 pm) to about 80 pm (in particular, to about 15pm) .

5. The feeding assembly according to any one of the preceding claims, wherein the duct (DU) has a width ranging from about 10 mm (in particular, from about 15 mm) to about 10 cm (in particular, to about 4 cm) at said stretch (ST) .

6. The feeding assembly according to any one of the preceding claims, wherein said stretch (ST) has a width ranging from about 3 cm to about 40 cm.

7. The feeding assembly according to any one of the preceding claims, wherein said stretch (ST) has a shape substantially tapered from the outer surface (ES) towards the inner surface (IS) .

8. The feeding assembly according to any one of the preceding claims, wherein the stretch (ST) has at least one lateral edge (LE) that connects the outer surface (ES) and the inner surface (IS) , which has a fluid-tight surface treatment .

9. The feeding assembly according to any one of the preceding claims, comprising a first feeding device (10) and at least one second feeding device (11) ; the first feeding device (10) comprises at least one respective first containing chamber (12) configured to contain a powder material (CA) of a first type and having at least one relative first output mouth (13) having a longitudinal extension; the second feeding device (11) comprises at leastone respective second containing chamber (14) configured to contain a powder material (CB) of a second type and having a relative second output mouth (15) having a longitudinal extension parallel to the longitudinal extension of the first output mouth (13) ; the first output mouth (13) has respective first passage zones (16) arranged in succession along the longitudinal extension of the first output mouth (13) ; the second output mouth (15) has respective second passage zones (17) arranged in succession along the longitudinal extension of the second output mouth (15) ; the feeding assembly (9) further comprises an operating device (18) , which is configured to allow the powder material (CA; CB) to get out through the first and / or the second passage zones (16, 17) and / or to prevent it from doing so and comprises a plurality of operating units (22) , each configured to adjust the passage of the powder material (CA; CB) through the respective first and / or second passage zone (16, 17 ) ; said duct (DU) being part of said first containing chamber (12) at the first output mouth (13) and / or of said second containing chamber (14) at the second output mouth (15) .

10. The feeding assembly according to claim 9, wherein each operating unit (22) comprises a respective transfer slider (23) , which has a transit channel (24) provided with at least one input (25; 28) and at least one output (26) arranged under the input (25; 28) , and a respective actuator (27) to move the transfer slider (23) to a first position (FP) , in which the transit channel (24) is connected to the first containing chamber (12) so that the powder material(CA) of the first type moves from the first containing chamber (12) to the transit channel (24) , and at least to a second position (SP) , in which the transit channel (24) is connected to the second containing chamber (14) so that the powder material (CB) of the second type moves from the second containing chamber (14) to the transit channel (24) ; each operating unit (22) further comprises a respective operating connection (33) , which is connected to the respective slider (23) and to the respective actuator (27) so as to transfer a movement generated by the actuator (27) to the slider (23) ; the feeding unit (9) comprises a plurality of groups(38) of said operating units (22) ; each group (38) comprises at least two operating units (22) contiguous with one another; each actuator (27) comprising a movable element(39) , connected to the respective operating connection (33) , and a moving system (39' ) for moving the movable element (39) in a respective defined direction (D) ; the defined directions (D) of the moving systems (39' ) of the operating units (22) belonging to a same group (38) of operating units (22) being different from and transverse to one another.

11. A compaction machine for compacting a powder material (CP) , comprising ceramic powder and mainly consisting of particles with dimensions smaller than about 600 m (in particular, smaller than about 500 pm) ; the compaction machine (2) comprises a compaction device (3) , which is arranged at a work station (4) and is configured to compact the powder material (CP) so as to obtain a layer of compacted powder (KP) ; a conveyor assembly(5) to transport the powder material (CP) along a first stretch (PA) of a given path in a conveying direction (A) from an input station (6) towards the work station (4) and the layer of compacted powder (KP) along a second stretch (PB) of the given path from the work station (4) to an output station (7) ; and a feeding assembly (9) , which is according to any one of the preceding claims and is configured to feed the powder material (CP) to the conveyor assembly (5) at the input station (6) ; in particular, the first feeding device (10) and the second feeding device (11) are arranged above the conveyor assembly (5) and the longitudinal extensions of the first output mouth (13) and of the second output mouth (15) are transverse (in particular, perpendicular) to the conveying direction (A) .

12. The compaction machine (2) according to claim 11, wherein the feeding assembly (9) comprises at least one containing chamber (12; 14) configured to contain the powder material (CP) and at least one transfer chamber (35) configured to receive the powder material (CP) from the containing chamber (12; 14) and to transfer the powder material (CP) to the conveyor assembly (5) transversely (in particular, perpendicularly) to the conveying direction (A) ; the transfer chamber (35) comprises said duct (DU) , which extends transversely (in particular, perpendicularly) to the conveying direction (A) ; in particular, the duct (DU) comprises a further wall arranged so as to face and upstream of said wall relative to the conveying direction (A) .

13. A plant for manufacturing ceramic articles (T) ; the plant (1) comprises a compaction machine (2) according to claim 11 or 12; a cutting assembly (47) for transverselycutting the layer of compacted powder (KP) so as to obtain slabs (48) , each having a portion of the layer of compacted powder (KP) ; and at least one firing kiln (51) for sintering the layer of compacted powder (KP) of the slabs (48) so as to obtain the ceramic articles (T) ; in particular, the firing kiln (51) is arranged along the given path downstream of a printing station (39) of said plant.

14. A process for feeding a powder material, comprising ceramic powder and consisting of particles mainly with dimensions smaller than about 600 m (in particular smaller than about 500 pm) and mainly with dimensions larger than about 50 pm (in particular, larger than about 90 pm) ; the method being implemented by a feeding assembly (9) according to any one of the claims from 1 to 10 and comprising at least one feeding step, during which the powder material moves along said duct (DU) and the pressure assembly feeds the gas (in particular, air) at a relative pressure (PP) ranging from about 5 mbar to about 1000 mbar to said outer surface (ES) so that at least a part of the gas flows through said stretch (ST) and reaches said passage (LU) .

15. The process according to claim 14 and comprising at least one interruption step, during which said powder material (CP) is stopped inside said duct (DU) ; the feeding step being subsequent to the interruption step; in particular, the method comprises a plurality of feeding steps and of interruption steps alternated with one another .

16. The process according to claim 14 or 15, wherein, during the feeding step, the powdered material moves along said duct (DU) and the pressure assembly feeds the gas (inparticular, air) at a relative pressure (PP) up to about 95 mbar (in particular, up to about 30 mbar) .

17. A method for compacting a powder material (CP) , comprising ceramic powder and consisting of particles mainly with dimensions smaller than about 600 m (in particular, smaller than about 500 pm) ; the method comprising a compaction step, during which a conveyor assembly (5) conveys the powder material (CP) along a first stretch (PA) of a given path in a conveying direction (A) from an input station (6) to a work station (4) and a layer of compacted powder (KP) along a second stretch (PB) of the given path from the work station (4) to an output station (7) ; during the compaction step, a compaction device compacts the powder material (CP) so as to obtain the layer of compacted powder (KP) ; the method further comprising the process for feeding the powder material (CP) according to any one of the claims from 14 to 16.

18. A process for manufacturing ceramic articles (T) ; the process comprises: the method according to claim 17; a cutting step, during which a cutting assembly (47) transversely cuts the layer of compacted powder (KP) so as to obtain slabs (48) , each having a portion of the layer of compacted powder (KP) ; and at least one firing step, during which a firing kiln (51) sinters the layer of compacted powder (KP) of the slabs (48) so as to obtain the ceramic articles (T) .

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