Plant and method for the manufacture of ceramic articles (Machine-translation by Google Translate, n

专利摘要:
Plant and method for the manufacture of ceramic articles. Plant for the manufacture of ceramic articles (T) comprising a first feeding device (9) and a second feeding device (10), which are adapted to feed a first powder (FP) and a second powder (SP), respectively, to a carrier group (5); the first and second powders (FP, SP) consisting of particles of different sizes and colors; the first feeding device (9) comprising two lateral discharge units (12) and at least one central discharge unit (13), which is arranged between said two lateral discharge units (12). (Machine-translation by Google Translate, not legally binding)
公开号:ES2890735A2
申请号:ES202130522
申请日:2021-06-07
公开日:2022-01-21
发明作者:Andrea Felice；Maurizio Colmi
申请人:Sacmi Imola SC ；
IPC主号:

专利说明:

[0002] PLANT AND METHOD FOR THE MANUFACTURE OF CERAMIC ARTICLES
[0004] CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0005] This application claims priority from Italian Patent Application No. 102020000013594 filed on June 8, 2020, the content of which is hereby incorporated by reference.
[0007] TECHNICAL SECTOR
[0008] The present invention relates to a plant and a method for manufacturing ceramic articles.
[0010] BACKGROUND OF THE INVENTION
[0011] In the field of the production of ceramic articles (in particular, slabs; more in particular, platelets) the use of machines for the compaction of semi-dry powder (ceramic powders; with a moisture content of about 5%-6%) is known. . These machines comprise ceramic powder feeding devices of different types.
[0013] These machines are often used to manufacture products that imitate natural stones, such as marble and/or granite. These products present internal veining randomly distributed within the thickness of the products.
[0015] In addition or as an alternative, it may be appropriate to use powders of different types to obtain articles with particular structural and/or physical characteristics.
[0017] In some cases, mixtures of powders of different colors are brought in a random distribution into cavities of steel molds and then compressed to obtain, for example, slabs of compacted powder.
[0019] It has been proposed to produce slabs with random distribution of powders of different colors also using continuous compacting machines comprising a conveyor group for transporting (substantially continuously) the powder material along a given path through a work station, in correspondence with which a compacting device is arranged, which is adapted, through the cooperation of pressure rollers, to compact the material powder in order to obtain a layer of compacted powder.
[0021] An example of a continuous machine for compacting ceramic powder is described in international patent application publication number WO2005/068146, by the same applicant as the present application.
[0023] It is also known to make (for example, by digital printing) a graphic decoration on (over) the layer of compacted ceramic powder in order to make the finished article more visually similar to a natural product.
[0025] However, the systems available up to now for compacting ceramic powders of different types have several drawbacks. Among them we mention the following. Dust distribution is random and therefore inherently non-reproducible. Very rarely the veining that forms in the thickness of the articles (and therefore visible by looking at the edge of the articles themselves) are in a coordinated position with respect to the surface decorations obtained by printing.
[0026] The aesthetics of the product is significantly affected, making the difference much more apparent compared to a natural product (eg marble).
[0028] In some cases it has been possible to improve the synchronization between the surface decoration and the veining inside the ceramic body, obtained with colored powders using some particularly innovative devices (see, for example, patent applications EP1787779A2, WO2018163124A1 and EP3424661A1 of the same applicant). It should be noted, however, that a very "flat" grain pattern is often obtained in the mass (i.e. with a median directrix at a small angle to the horizontal plane) which is not always sufficiently "natural" ( see, for example, Figure 12).
[0030] The veins of natural materials (see, for example, Figure 13) are also richer in color and are not endowed (contrary to what often happens with state-of-the-art ceramic materials) with relatively extensive single-color areas that stand out abnormally to the eye of the observer.
[0031] The object of the present invention is to provide a plant and a method that make it possible to overcome, at least partially, the drawbacks of the known art and that, at the same time, are easy and cheap to obtain.
[0032] SUMMARY EXPLANATION OF THE INVENTION
[0034] According to the present invention, there is provided a plant and a method for the manufacture of ceramic articles as defined in the following independent claims and, preferably, in any of the claims which depend, directly or indirectly, on the independent claims.
[0036] BRIEF DESCRIPTION OF THE FIGURES
[0038] The invention is described below with reference to the attached drawings, which illustrate some non-limiting examples of embodiment, in which:
[0040] - Figure 1 is a schematic side view of a plant according to the present invention;
[0042] - Figure 2 is a front and schematic view of an element of the machine 1 during operation;
[0044] Figure 3 is a schematic front view of a different embodiment of the element of Figure 2 during operation;
[0046] Figure 4 is a schematic front view of a different embodiment of the element of Figure 2 during operation;
[0048] - Figure 5 is a front and schematic view of the element of Figure 4 with the addition of some details during operation;
[0050] - Figure 6 illustrates, for comparative purposes, the behavior of a powder with a low angle of repose;
[0052] - Figure 7 is a schematic and plan view of a part of the plant of Figure 1 during operation;
[0054] - Figures 8 to 11 are front views of successive work steps;
[0055] - Figure 12 is a photograph of a ceramic article obtained by a state-of-the-art machine;
[0057] - Figure 13 is a photograph of a natural marble slab;
[0058] - Figure 14 is a schematic and plan view of a different embodiment of the part of the plant of Figure 7 during operation;
[0059] - Figure 15 is a schematic front view of the element of Figure 5 in the embodiment of Figure 14;
[0061] - Figures 16 to 18 are schematic and plan views of a different embodiment of the element of Figure 5 in successive stages of work;
[0063] - Figure 19 is a schematic side view of a part of the plant of Figure 14 including the element of Figure 15;
[0065] - Figure 20 is a schematic and plan view of a different embodiment of the part of the plant of Figure 14 during operation;
[0066] - Figure 21 is a front and schematic view of the element of Figure 5 in the embodiment of Figure 20;
[0068] - Figure 22 is a schematic side view of a part of the plant of Figure 20 including the element of Figure 21;
[0070] - Figure 23 is a schematic and plan view of a different embodiment of the part of the plant of Figure 20 during operation;
[0071] - Figure 24 is a schematic front view of the element of Figure 5 in the embodiment of Figure 23;
[0073] - Figure 25 is a schematic side view of a part of the plant of Figure 23 including the element of Figure 24;
[0075] - Figure 26 is a schematic and plan view of a different embodiment of the part of the plant of Figure 23 during operation;
[0076] - Figure 27 is a front and schematic view of the element of Figure 5 in the embodiment of Figure 26;
[0078] - Figure 28 is a schematic side view of a part of the plant of Figure 26 including the element of Figure 27;
[0080] - Figure 29 is a schematic and plan view of a form of different embodiment of the plant part of Figure 26 during operation;
[0081] - Figure 30 is a front and schematic view of the element of Figure 5 in the embodiment of Figure 29;
[0083] - Figure 31 is a schematic side view of a part of the plant of Figure 29 including the element of Figure 30;
[0085] - Figure 32 is a schematic and plan view of a different embodiment of the part of the plant of Figure 29 during operation;
[0086] - Figure 33 is a schematic front view of the element of Figure 5 in the embodiment of Figure 32;
[0088] - Figure 34 is a schematic side view of a part of the plant of Figure 32 including the element of Figure 33;
[0090] - Figure 35 is a schematic and plan view of a different embodiment of the part of the plant of Figure 29 during operation; Y
[0092] - Figure 36 is a schematic and plan view of the plant of Figure 35 in a different operating configuration.
[0094] DETAILED DESCRIPTION
[0095] According to a first aspect of the present invention, in Figure 1, a plant for manufacturing ceramic articles T as a whole is indicated by 1. The plant 1 is provided with a compacting machine 2 for compacting the CP powder material, which comprises ceramic powder (in particular, the CP powder material is ceramic powder; more particularly, the ceramic powder has a moisture content of about 5%-6%).
[0097] In particular, the ceramic articles T produced are slabs (more precisely, platelets).
[0099] The machine 2 comprises a compacting device 3, which is arranged in correspondence with a work station 4 and is adapted to (configured to) compact the powder material CP to obtain a layer of compacted powder KP; and a conveyor group 5 (configured) to transport (so substantially continuous) the powder material CP along a section PA of a given path from an input station 6 to the work station 4 (in particular, in a forward direction A) and the compacted powder layer KP from the workstation 4 along a section PB of the determined path to an output station 7 (in particular, in the direction A). In particular, the given path consists of sections PA and PB.
[0101] According to non-limiting embodiments, the compaction device 3 is configured to exert a pressure of at least approximately 350 kg/cm2 (in particular, at least approximately 380 kg/cm2; in particular, up to approximately 450 kg/cm2; more on particular, up to about 420 kg/cm2) on the CP powder material.
[0103] The machine 2 is also provided with a feeding group 8, which is configured to feed the powder material CP to the conveyor group 5, in particular in correspondence with the input station 6 (more in particular, a zone CZ of the conveyor group 5 ).
[0105] The feeding group 8 comprises a feeding device 9 (see, in particular, Figures 1 and 7), which is configured to feed a first powder FP to (directly in contact with) a first part (of the CZ zone) of the conveyor group 5 (in particular, directly in contact with conveyor group 5) so that the first powder FP substantially has a first thickness (of height H) on conveyor group 5 (see, in particular, Figures 3 and 5) . In particular, the feeding device 9 is configured to feed the first powder FP to the conveyor group 5 to arrange it on the first part (of the zone CZ) of the conveyor group 5.
[0107] More precisely, although not necessarily, the feeding device 9 is arranged along the section PA. Even more precisely, the feeding device 9 is arranged in correspondence with the input station 6.
[0109] The CP powder material comprises (in some non-limiting cases, consists of) the first FP powder.
[0111] Advantageously, although not necessarily, the feeding device 9 is configured to feed the first FP powder that is (predominantly; in particular, at least about 70%; more particularly, at least about 85%; even more particularly, at least approximately 95% by weight with respect to the total weight of the first FP powder) made up of particles having sizes less than approximately 180 μm (in particular, greater than approximately 30 μm) and, in in particular, it has an angle of repose greater than about 55°, in particular greater than about 65°, more in particular greater than about 80° (more in particular, less than about 90°).
[0113] The sizes are obtained by successive sieving with sieves with holes of decreasing dimensions (diameters). The diameter of the holes in the first screen that do not allow the particles to pass indicates the sizes (ie diameter) of the particles.
[0115] Measurements by successive sieves are carried out whenever the sizes (or diameters) of the particles and of the sieve holes allow it (in particular, up to a minimum of 0.05 mm). Below these dimensions (in particular, 0.05 mm), particle sizes are measured as mean diameter D(v,0.5) measured by a laser particle sizer - in particular, using a Mastersizer Microplus Ver. 2.19 (Malvern Instruments® Ltd). In particular, the mean diameter measurements are made according to ISO 13320:2009.
[0117] Advantageously, although not necessarily, the feeding group 8 comprises a feeding device 10, which is configured to feed a second powder SP (predominantly by weight; in particular, by at least about 70%; more particularly, by at least about 85%; even more particularly, at least about 95% by weight with respect to the total weight of the second powder SP) made up of particles having sizes greater than about 200 μm (in particular, less than about 600 ^ m) in (directly in contact with) a second part other than said first part (of zone CZ) of the conveyor group 5. In particular, the second powder SP has an angle of repose of less than about 50°, more particularly less at about 45° (in particular, greater than about 20°).
[0119] More precisely, although not necessarily, the feeding device 10 is configured to feed the second powder SP to the conveyor group 5 by arranging it in the second part (of the zone CZ) of the conveyor group 5.
[0120] Angles of repose are measured as provided by ASTM C1444-00. The comparison between Figures 6 and 3 (and between Figures 2 and 4) shows the different behavior of the spray-dried PP and PPP powders at a low angle of repose (Figures 6 and 2) and the first (micronized) FP powder, which advantageously, although not limiting, it has a high angle of repose.
[0122] The powder material CP comprises the second powder SP and the first powder FP. More precisely, although not necessarily, the powder material CP is constituted by the first powder FP and the second powder SP.
[0124] Advantageously, although not necessarily, the plant 1 (more precisely, the machine 2) comprises a compression device 11 (Figures 1, 7 and 8), which is arranged in correspondence with a compression station 11* (in particular, along along the first section PA; more particularly in correspondence with the input station 6) upstream (in the direction A) of the work station 4 and downstream (in the direction A) of the feeding device 9 and is adapted for (configured to) compress the first FP powder so that the first FP powder has a second thickness less than the aforementioned first thickness.
[0126] It has been experimentally observed that, thanks to the combination of the feeding device 9, the compression device 11 and the compaction device 3, it is possible to obtain an improved handling and compaction of the powder material (in particular, of the first powder). FP). In this regard, it should be noted that the powder material (which already tends by itself, being micronized - see above and compare Figures 6 and 2, to stay in position) is initially partially compressed so that the position of the different particles remain even more fixed. In addition, the use of the compression device 11 and the compaction device 3 (in other words, the fact that the compaction takes place in two successive stages) makes it possible to obtain a more homogeneous compaction and, therefore, ceramic articles T with stresses reduced internal. In this way, the action of compaction, and therefore evacuation of the air present between the grains of powder, is subdivided into two distinct stages. This elimination of air is very important for a good compaction of the ceramic mass.
[0128] It has also been experimentally observed that, thanks to the combination of the feeding devices 9 and 10 and the compression device 11, it is surprisingly possible to obtain compacted powder KP and ceramic articles T which they exhibit well-defined FP first powder-containing zones and, at the same time, excellent strength (low internal stresses).
[0130] According to some non-limiting embodiments, the compression device 11 comprises (is) a roller transverse (in particular, substantially perpendicular) to direction A. In particular (Figure 8), said roller is separated from the conveyor group 5 by a height H H.
[0132] More precisely, although not necessarily, the feeding device 9 is configured to feed the second powder SP to the conveyor group 5 so that the second powder SP presents a third thickness on the conveyor group 5. The third thickness is less than the first thickness. and, in particular, it is substantially equal to the second thickness (and corresponds to the height HH).
[0134] In particular (Figures 1 and 11), it should be noted that the compacting device 3 is configured to compress the powder material CP (which, more particularly, is fed to the compacting device 3 with a thickness substantially equal to the second thickness - and to the third thickness, substantially corresponding to the height HH) so that the layer of compacted powder KP has a fourth thickness (corresponding - equal - to a height HHH), less than the second (and third) thickness (and therefore the height HH).
[0136] Advantageously, although not necessarily, the heights H, HH and HHH are selected such that the density of the compacted powder layer KP is substantially homogeneous.
[0138] More in particular, the first thickness, the second thickness (hence also the third thickness) and the fourth thickness (and thus the heights H, HH and HHH) are selected such that the following relationship is satisfied:
[0140] D1 = D2 ± 0.030 kg/dm3 (preferably, but not necessarily, D1 = D2 ± 0.020 kg/dm3)
[0142] where
[0144] D1 = HH/HHH x SD
[0146] D2 = H/HHH x DF
[0147] where DS is the apparent density of the second powder SP; DF is the bulk density of the first FP powder.
[0149] Advantageously, although not necessarily (Figures 1 and 7), the feed device 9 is arranged upstream (in the forward direction (A)) of the feed device 10; compression device 11 is arranged along section PA between feed device 9 and feed device 10.
[0151] According to some non-limiting and unillustrated embodiments, the feed device 9 is arranged downstream (in the forward direction (A)) of the feed device 10; compression device 11 is arranged along section PA downstream of feed device 9.
[0153] Advantageously, although not necessarily, the feeding device 9 (Figures 2, 4 and 5) comprises at least two lateral discharge units 12 and at least one central discharge unit 13, which is configured to carry (arrange) a first part FFP of the first FP powder onto the conveyor group 5. Each side discharge unit 12 is configured to dispose (carry) a respective second part SFP of the first FP powder to the sides and in contact with the first part FFP of the first FP powder, so that the second parts SFP of the first powder FP laterally support and limit the movements of the first part FFP of the first powder FP.
[0154] In this way, a positioning of the first FFP part is obtained (compare Figure 2 with Figure 6 - in relation to spray-dried PP and PPP powders with a relatively low angle of repose, and Figure 4 with Figure 3 - in relative to the first FP powder with a relatively high angle of repose) even more accurate and stable.
[0156] In particular, the central discharge unit 13 is arranged between said at least two lateral discharge units 12.
[0158] Advantageously, although not necessarily, the central discharge unit 13 has an outlet mouth 14 directed towards the conveyor group 5 (in particular downwards) and separated from the conveyor group 5 by the height H substantially equal to the first thickness. In particular, each side discharge unit 12 also has a respective outlet mouth 15 directed towards the conveyor group 5 (downwards) and separated from the conveyor group 5 by the height H substantially equal to the first aforementioned thickness.
[0160] According to some non-limiting embodiments, the lateral discharge units 12 and the central discharge unit 13 are (substantially integral with each other and) aligned in an alignment direction B. More particularly, direction B is transverse to direction A.
[0162] Advantageously, although not necessarily, the feeding group 8 (more precisely, the feeding device 9) comprises a rotation unit 16 which is configured to rotate the lateral discharge units 12 and the central discharge unit 13 (to change the orientation of the relative position of the side discharge units 12 and the central discharge unit 13).
[0164] In this way it is possible to modify (or keep unchanged) the width of the first powder FP in the conveyor group 5.
[0166] More precisely, although not necessarily, the rotation unit 16 is configured to rotate the side discharge units 12 and the central discharge unit 13 to change the alignment direction B. In particular, the alignment direction B is transverse to the direction A.
[0168] In particular, the rotation unit 16 is configured to rotate the side discharge units 12 and the central discharge unit 13 about an axis AA substantially perpendicular to the direction A of advance. More in particular, the axis AA is substantially perpendicular to a transport plane of the conveyor group 5, in which transport plane the first powder FP lies, while, in use, it is fed to the feeding device 10. For example, the unit The movement mechanism may comprise an electric motor configured to act on a shaft integral with the lateral discharge units 12 and the central discharge unit 13.
[0170] It should be noted that, in particular, in use, the first powder FP (and possibly also the second powder SP) lies on said transport plane of the conveyor group 5, while being fed (along the section PA) towards the station of outlet 7 (to compaction device 3).
[0172] Advantageously, although not necessarily (Figures 5 and 7), the feeding group 8 comprises a movement unit 17, which is adapted to move the feeding device 9 (in particular, in a direction C transverse to the direction A of advance) so that the first feeding device 9 can carry out a distribution (in particular, in a certain way) of the first powder FP in the conveyor group 5, in particular in the aforementioned transport plane.
[0174] The combination of the movement unit 17 and the rotation unit 16 is particularly effective. In this way it is in fact possible to realize different distributions by also regulating the width of the rows of the first powder FP (and/or of its first part FFP).
[0176] For example, the movement unit 17 may comprise a raised guide (with respect to the conveyor group 5), which extends in the direction C and on which the side discharge units 12 and the central discharge unit 13 are mounted in a fixed manner. slider
[0178] Advantageously, although not necessarily (Figure 1), the plant 1 comprises a printing device 18, which is configured to carry out a graphic decoration on (over) the layer of compacted ceramic powder KP in correspondence with a printing station 19 along of the determined route (in particular along the section PB) downstream of the work station 4. In particular, the graphic decoration is coordinated with the distribution of the first powder FP.
[0180] According to some non-limiting embodiments, the plant 1 also comprises a control unit 20, in which a reference distribution is memorized and configured to control the feeding group 8 (in particular, together with the conveyor group 5) of so that the feeding device 9 performs the mentioned distribution (of a determined shape) of the first powder FP on the conveyor group 5 on the basis of the reference distribution (in particular, to substantially reproduce the reference distribution). In particular, the control unit 20 is configured to control the printing device 19 to perform graphic decoration based on the reference distribution.
[0182] Advantageously, although not necessarily, the plant 1 comprises a determination group 21 (in particular, comprising an optical detector), which is configured to detect (and determine) said distribution (of a determined shape) of the first FP powder on the conveyor group 5. In these cases, in particular, the control unit 20 is configured to control the printing device 19 to carry out the graphic decoration based on the reference distribution and depending on what the determination group 21 detects, more particularly depending on one or more differences between the reference distribution and said distribution (of determined form) of the first powder in the conveyor group (adapting -deforming - the graphic decoration).
[0184] In particular, the feed device 9 is arranged in correspondence with a feed station 22 (along the section PA) and the feed device 10 is arranged in correspondence with a respective feed station 23 (along the section PA). PA section). The feeding stations 22 and 23 are part of the input station 6. According to some non-limiting embodiments, the feeding station 22 is arranged along the section PA upstream (in the direction A) of the feeding station. feeding 23.
[0186] According to some non-limiting embodiments (Figures 1, 7 and 9), the feeding device 10 comprises a containment chamber 24 (for example, a hopper), which is configured to contain the second powder SP and to transfer the second powder SP to the conveyor group 5 in correspondence with the feeding station 23. In particular, the containment chamber 24 has an outlet mouth 25 (Figure 9), which is configured to pass the second powder SP and is directed towards the conveyor group 5 (down).
[0188] More precisely, although not necessarily, the outlet mouth 25 is separated from the conveyor group 5 by the height HH substantially equal to the third thickness.
[0190] Advantageously, although not necessarily, the outlet mouth 25 of the containment chamber 24 has an extension perpendicular to the determined path (more precisely to direction A) greater than the sum of the extensions perpendicular to the determined path (more precisely to direction A). ) from outlets 14 and 15 of central discharge unit 13 and side discharge units 12.
[0192] Advantageously, although not necessarily (Figure 1), the plant 1 comprises an extraction device 26, which is configured to remove a superficial part of the powder material CP arranged in the conveyor group in correspondence with an extraction station 27 arranged downstream ( with respect to the direction of advance A), in particular along the first section PA, of the feeding group 8.
[0193] In this way, it is at least partially possible to reduce possible surface admixtures between the first powder FP and the second powder SP. These advantages are particularly useful when the device 10 has a containment chamber 24 and an outlet 25 (as described above). In these cases, the second powder SP present in the containment chamber 24 disposed in correspondence with the first powder FP does not substantially pass through the outlet mouth 25, but comes into contact with the first powder. Therefore, it is possible that some particles of the second powder SP pass through and/or, by contact, cause a displacement of the first powder FP. The second powder SP disposed in correspondence with the conveyor group 5 that is no longer occupied by the first powder FP passes through the outlet mouth 25 and reaches the conveyor group 5 (in particular, depositing itself on the transport plane mentioned above) .
[0195] In particular, the extraction device 26 is configured to extract a surface part of the powder material CP by suction.
[0197] Advantageously, although not necessarily, the plant 1 comprises another application group 28 for at least partially covering the (a layer of) powder material CP with a layer of another powder material. In particular, the application group 28 is arranged along the determined path (more precisely along the section PA) upstream of the work station 4 (and upstream of the printing station 19). Thanks to the application group 28, a (thin) layer of neutral color is obtained, on which the printing operations (after compaction) lead to higher quality results.
[0199] In particular, the machine 1 also comprises a cutting unit 29 for transversely cutting (in particular, in direction A) the layer of compacted ceramic powder KP to obtain slabs 30, each of which has a part of the powder layer compacted ceramic KP. More particularly, the cutting group 29 is arranged along the section PB of the determined path (between the work station 4 and the printing station 19). The slabs 30 comprise (consist of) compacted ceramic powder KP.
[0201] Advantageously, although not necessarily, the cutting group 29 comprises at least one cutting blade 31, which is adapted to come into contact with the layer of compacted ceramic powder KP in order to cut it transversely.
[0202] According to some non-limiting embodiments, the cutting group 29 also comprises at least two other blades 32, which are arranged on opposite sides of the section PB and are configured to cut the layer of compacted ceramic powder KP and define lateral edges of the layers. slabs 30 (and substantially parallel to direction A), possibly subdividing each slab 30 into two or more longitudinal portions. In some specific cases, the cutting group 29 is like the one described in the patent application with publication number EP1415780.
[0204] In particular, the plant 1 comprises at least one firing furnace 33 to sinter the compacted powder layer KP of the slabs 30 to obtain the ceramic articles T. More particularly, the firing furnace 33 is arranged along the determined path (more precisely along section PB) downstream of printing station 19 (and upstream of output station 7).
[0206] According to some non-limiting embodiments, the plant 1 further comprises a dryer (known per se and not illustrated) arranged along the section PB downstream of the workstation 4 and upstream of the printing station 19.
[0207] According to some non-limiting embodiments, the conveyor group 5 comprises a conveyor belt 34 which extends (and is adapted to move) from the input station 6 and through the work station 4, along the (more precisely - at least - part of the) mentioned determined route.
[0209] According to some advantageous but non-limiting examples of embodiment, the feeding group 8 is configured to bring a layer of powder material CP (not compacted) to the (on; and, in particular, directly in contact with) conveyor belt 34 ( in correspondence with the entrance station 6). In these cases, more precisely, the feeding device 9 is configured to bring the first powder FP (not compacted) to (on; and, in particular, directly in contact with) the conveyor belt 34 (in correspondence with the feeding station 22); additionally or alternatively, the feeding device 10 is configured to bring the second powder SP (not compacted) to (on; and, in particular, directly in contact with) the conveyor belt 34 (in correspondence with the feeding station 23) .
[0211] In particular, the compaction device 3 is adapted (configured to) exerting on the layer of ceramic powder CP (comprising the first powder FP and the second powder SP) a pressure transverse (in particular, perpendicular) to the surface of the conveyor belt 34 .
[0213] According to some non-limiting embodiments, a succession of conveyor rollers is provided downstream of belt 34.
[0215] According to some non-limiting embodiments, the compaction device 3 comprises at least two compression rollers 35 arranged on opposite sides (one up and one down) of the conveyor belt 34 to exert pressure on the powder material CP to compact the material. own CP powder material (and obtain the compacted powder layer KP).
[0217] Although only two rollers 35 are illustrated in Figure 1, according to some variants, it is also possible to provide a plurality of rollers 35 arranged above and below the conveyor belt 34, as described, for example, in patent EP1641607B1, of which other details of the compaction device 3 can be inferred.
[0219] Advantageously (as in the embodiment illustrated in Figure 1), although not necessarily, the compaction device 3 comprises a pressure belt 36, which converges towards the conveyor belt 34 in the direction A of advance. In this way, a gradually increasing pressure (from top to bottom) in the direction A is exerted on the powder material CP to compact it.
[0221] According to some specific non-limiting embodiments (such as the one illustrated in Figure 1), the compaction device also comprises an antagonist belt 37 arranged on the opposite side of the conveyor belt 34 with respect to the pressure belt 36 to cooperate with the conveyor belt 34 to provide a suitable counter to the downward force exerted by the pressure belt 36. In particular, the pressure belt 36 and counter belt 37 are (primarily) metal (steel) so that they cannot substantially deform while pressure is exerted on the ceramic powder.
[0223] According to some embodiments not illustrated, the antagonist belt 37 and the conveyor belt 34 coincide. In these cases, the strap 34 is (mostly) metal (steel) and the counter strap 37 is absent.
[0224] According to some non-limiting examples, the containment chamber 24 comprises two walls (transverse, in particular perpendicular, to direction A) facing each other (and preferably substantially parallel).
[0226] With particular reference to Figures 14 and 15, according to some non-limiting embodiments, the feeding device 10 comprises two lateral bulkheads 38 (which are configured to laterally contain the second powder SP while it descends from the outlets 15 in the transporter group 5). The side discharge units 12 and the central discharge unit 13 are arranged between the side bulkheads 38.
[0228] Thanks to the lateral bulkheads 38, the tendency of the first FP powder to slide laterally and, therefore, the tendency of the second SFP parts of the first FP powder to widen (spread) is reduced.
[0230] In particular, the side bulkheads 38 are integral with the side discharge units 12 (and therefore move and rotate together with the side discharge units 12).
[0232] More precisely, although not necessarily, the lateral bulkheads 38 (substantially parallel to each other) extend from the outlets 15 towards the conveyor group 5 (in particular, towards the belt 34), in particular to reach a short distance from the conveyor group 5 (in particular, a short distance from the belt 34; more particularly, a short distance from the aforementioned transport plane of the conveyor group 5).
[0234] Advantageously, although not necessarily, the side bulkheads 38 extend towards the conveyor group 5 substantially perpendicular to direction A.
[0236] According to some non-limiting embodiments, the feeding device 9 comprises two central bulkheads 39 (which are configured to laterally contain the first powder SP while it descends from the outlet mouth 14 in the conveyor group 5). The two central bulkheads 39 are each arranged between the central discharge unit 13 and a respective one of the two lateral discharge units 12.
[0238] Thanks to the central bulkheads 39, the tendency of the first FP powder to slide laterally is reduced and, therefore, the tendency of the first FFP part of the first FP powder to swell (spread).
[0240] In particular, the central bulkheads 39 are integral with the central discharge units 13 (and therefore move and rotate together with the central discharge units 13).
[0242] More precisely, although not necessarily, the central bulkheads 39 (substantially parallel to each other) extend from the outlet 14 towards the conveyor group 5 (in particular, towards the belt 34), in particular to reach a short distance from the conveyor group 5 (in particular, a short distance from the belt 34; more particularly, a short distance from the aforementioned transport plane of the conveyor group 5).
[0244] Advantageously, although not necessarily, the central bulkheads 39 extend towards the conveyor group 5 substantially perpendicular to direction A.
[0246] Advantageously, although not necessarily, the central bulkheads 39 have a plurality of through holes. The through holes allow a partial interpenetration between the first part FFP of the first powder FP and the second part SFP of the first powder FP. In this way, in particular when the first FFP part and the second SFP part have different colors, a more natural aesthetic effect is obtained.
[0248] According to some non-limiting embodiments (and as illustrated in Figure 7), the roller of the compression device 11 is arranged fixed in a certain position between the feed device 9 and the feed device 10.
[0250] Alternatively (as illustrated in Figures 14, 19, 20, 22, 23, 25, 26, 28, 29 and 31) according to some embodiments, the compression device roller 11 is integrally mounted to the feed device 9. In this way, the roller is moved and/or rotated by the movement unit 17 and/or the rotation unit 16, respectively, together with the feeding device 9 (more precisely, together with the lateral discharge units 12 and the center discharge unit 13.
[0252] The structure and roller arrangement of the compression device 11 of the embodiments of Figures 14, 16, 19-29 is simpler and less bulky.
[0254] With particular reference to Figures 16 to 18, according to some forms of non-limiting embodiment, the central discharge unit 12 has a cross section (in particular, the outlet mouth 14) of an elongated shape. For example, said elongated shape is substantially rectangular (as illustrated in Figures 16-18) or elliptical.
[0256] Advantageously, although not necessarily, the compaction device 3 comprises a rotation device for rotating the outlet 14 (in particular, the central discharge unit 13) around an axis transverse (in particular, substantially perpendicular) to the plane conveyor group 5 (on whose transport plane the first powder FP lies, while, in use, it is fed to the compacting device 3). More precisely, although not necessarily, the rotation device acts selectively on the central discharge unit 13 without causing the lateral discharge units 12 to rotate.
[0258] In this way it is possible to vary the width of the first zone FZ. For example, when the first and second powders FP and SP have different colors and it is desired to reproduce a natural material, by varying the width of the first zone FZ a more aesthetically realistic effect can be obtained.
[0260] More in particular, said axis is transverse (substantially perpendicular) to the direction A of advance. Even more particularly, this axis passes through the center of the outlet 14 (in particular, of the central unit 13).
[0262] For example, the rotation device may comprise an electric motor configured to act on a shaft integral with the central discharge unit 13.
[0263] Advantageously, the compaction device 3 comprises a containment system to push (for example, by means of springs) the lateral unloading units 12 towards the central unloading unit 13 to keep them in contact with the central unit 13 itself (while the central unit 13 rotates on itself).
[0264] Advantageously, although not necessarily (Figures 20-25), the central discharge unit 13 is configured to feed (carry) the first part FFP of the first powder FP to (on) the conveyor group 5 (more precisely, on the belt 34; more precisely, on the transport plane); the first part FFP is a micronized powder (predominantly made up of particles with sizes less than about 180 μm, in particular greater than about 30 μm). The side discharge units 12 instead are configured to supply (carry) the second part SFP of the first powder FP to (on) the conveyor group 5 (more precisely, on the belt 34; more precisely, on the transport plane); the second SFP part is an atomized powder (predominantly made up of particles with sizes greater than 200 μm, in particular less than 600 μm).
[0266] In this way, the use of micronized powder (more difficult to feed along the ducts) is limited to the area that is most important to maintain its shape.
[0268] As can be seen more easily by looking at Figure 24, in particular (in these cases), the central discharge unit 13 is configured so that the first part FFP of the first powder FP that is deposited on the conveyor group 5 (more precisely, on the belt 34, more precisely on the transport plane) by the central unloading unit 13 itself presents substantially the first thickness (of height H - on the conveyor group 5); the side discharge units 12 are configured so that the second part SFP of the first powder FP deposited on the conveyor group 5 (more precisely, on the belt 34; more precisely, on the transport plane) by the side discharge units themselves 12 presents substantially the second thickness (or third thickness - of height HH - on the conveyor group 5).
[0270] In other words, in particular, the outlet mouth 14 is arranged at the height H while the outlet mouths 15 are arranged at the height HH of the conveyor group 5 (more precisely, of the belt 34; more precisely, of the plane of transport).
[0272] In particular, it should be noted that, in this way, the compression device 11 (with reference to the embodiment of Figures 20-22) does not act on the second part SFP of the first powder FP deposited on the conveyor group 5 and ( for all embodiments of Figures 20-25) this second SFP part does not interfere with the power device 10.
[0274] With particular reference to Figures 20-22, according to some non-limiting embodiments, the side discharge units 12 are arranged (along the section PA) downstream (in the direction A) of the central discharge unit 13 and, in particular, downstream (always in direction A) also from the compression device 11.
[0275] Advantageously, although not necessarily, the lateral 12 and central 13 unloading units are in any case integral with each other (and therefore move together by the rotation unit 16 and the movement unit 17).
[0277] Advantageously, although not necessarily, the feeding device 9 also comprises a suction group 40, which is configured to remove (suction) the possible particles of the first part FFP of the first powder FP arranged laterally to the first zone FZ (and, in particular, which are eventually not adequately compacted by the compression device 11). In this way, the risk of the ceramic articles T presenting aesthetic defects (for example, in the form of burrs) is reduced.
[0279] In particular, the suction group 40 is arranged (along the section PA) downstream (in the direction A) of the compression station 11*. In other words, the suction group is arranged to remove possible particles downstream (in direction A) of the compression station 11* and upstream (in direction A) of the side discharge units 12.
[0281] According to some non-limiting embodiments, the suction group 40 comprises two suction heads 41 arranged on opposite sides of the first zone FZ (in particular, downstream of the compression station 11* upstream of the side discharge units 12 ).
[0283] Figures 23-25 illustrate a variant of the plant 1 (in particular, the feeding device 9 and the compaction device 11) of Figures 20-22. In this case, the side discharge units 12 are arranged upstream of the compaction station 11* and partially aligned (in direction B) with the central discharge unit 13.
[0285] Advantageously, although not necessarily (Figures 26-31), the central discharge unit 13 is configured to feed (carry) the first part FFP of the first powder FP to (on) the conveyor group 5 (more precisely, on the belt 34; more precisely, on the transport plane); the first part FFP is an atomized powder. The side discharge units 12 instead are configured to supply (carry) the second part SFP of the first powder FP to (on) the conveyor group 5 (more precisely, on the belt 34; more precisely, on the transport plane); the second SFP part is a micronized powder (predominantly made up of particles with sizes less than about 180 μm, in particular greater than about 30 μm).
[0287] In this way, the micronized powder (harder to feed down the chutes) is not used in the area that may require particularly narrow chute feeds (eg where fine graining is desired).
[0289] As can be seen more easily by looking at Figure 27, in these cases, in particular, the central discharge unit 13 is configured so that the first part FFP of the first powder FP that is deposited on the conveyor group 5 (more precisely, on the belt 34 (more precisely, on the transport plane) by the central unloading unit 13 itself presents substantially the second thickness (or third thickness - height HH - on the conveyor group 5); the side discharge units 12 are configured so that the second part SFP of the first powder FP deposited on the conveyor group 5 (more precisely, on the belt 34; more precisely, on the transport plane) by the side discharge units themselves 12 substantially presents the first thickness (of height HH - above the conveyor group 5).
[0291] In other words, in particular, the outlet mouth 14 is arranged at the height HH while the outlet mouths 15 are arranged at the height H of the conveyor group 5 (more precisely, of the belt 34; more precisely, of the plane of transport).
[0293] In particular, it should be noted that, in this way, the compression device 11 (with reference to the embodiment of Figures 26-28) does not act on the first part FFP of the first powder FP deposited on the conveyor group 5 and ( for all the embodiments of Figures 26-31) this first part FFP does not interfere with the feeding device 10.
[0295] With particular reference to Figures 26-28, according to some non-limiting embodiments, the central discharge unit 13 is arranged upstream (in direction A) of the compaction station 11* and is partially aligned with the compaction units. side discharge 12.
[0297] Figures 29-31 illustrate a variant of the plant 1 (in particular, the feeding device 9 and the compaction device 11) of Figures 26-28. In this case, the central discharge unit 13 is arranged (along the section PA) downstream below (in direction A) the compaction station 11* and the feeding device 9 comprises a dividing element 42, which is adapted to limit (prevent) the second part SFP of the first powder FP carried on the conveyor group 5 from a first of the side discharge units, on the one hand, and the second part SFP of the first powder FP carried on the conveyor group 5 from a second of the side discharge units, on the other hand, come closer.
[0298] In particular, the dividing element 42 is arranged between the side discharge units 12 and extends through the station 11* to the central discharge unit 13. More precisely, the dividing element 42 is shaped to follow the profile of the discharge device. compression 11 (even more precisely from its compression roller), in particular without coming into contact with it.
[0300] With particular reference to Figures 29-31, according to some non-limiting embodiments, the central discharge units 13 are arranged downstream (in direction A) of the side discharge units 12 and, in particular, also downstream. (always in direction A) of the compression device 11.
[0302] Advantageously, although not necessarily, the lateral 12 and central 13 unloading units are in any case integral with each other (and therefore move together by the rotation unit 16 and the movement unit 17).
[0304] According to some non-limiting embodiments (see, in particular, Figures 32-34), the feeding device 9 comprises a single discharge unit 13 for feeding the first powder FP to the (over - over the entire useful surface of) the group conveyor 5 (more precisely, on the belt 34; more precisely, on the transport plane), where the first powder FP is (completely) a micronized powder (predominantly made up of particles having sizes less than about 180 μm, in particular larger than about 30 ^m). In other words, the feed device 9 is configured to produce a field filled with micronized FP powder (consisting predominantly of particles having sizes less than about 180 µm, in particular greater than about 30 µm).
[0306] In this way it is possible to obtain particular graphic effects both on the surface and in the mass.
[0307] It has been experimentally observed that (even in these cases) the presence of both the compression device 11 and the compaction device 3 remains advantageous.
[0309] In fact, in this way a better and more homogeneous compression of the FP (micronized) powder is obtained. A single compression leads to a heterogeneous KP compacted powder (with denser zones and less dense zones). This heterogeneity had not been detected particularly when spray-dried powder was previously used.
[0311] In this sense, it has been experimentally observed that the micronized powder tends to hinder (presumably by its very nature - fine grains and irregular in shape) the escape of the air present in the soft mass. On the contrary, the atomized powder (presumably because of its spherical and regular shape) facilitates more the elimination of air during pressing, which therefore benefits less from the use of the additional compression device 11.
[0313] According to some non-limiting embodiments (see in particular Figure 32), the plant 1 further comprises at least one tracer device 44, which is configured to insert another powder OP different from the first powder FP (for example, of different color) and is arranged (along the section PA) upstream (in direction A) of the compaction device 3 and downstream (in direction A) of the entry station 6.
[0315] In this way it is possible to create particular aesthetic effects (eg graining) potentially for the entire thickness of the CP powder material.
[0317] In particular, each tracer device 44 comprises an aspirator to remove part of the first FP powder (for example, to create a groove) and a deposition unit configured to insert the other aforementioned OP powder where the first FP powder has been removed (for example, to create a groove). example, in the groove).
[0319] According to some non-limiting embodiments, each tracer device 44 is as described in patent applications having publication numbers EP1787779A3 and WO2005/090024A1 of the same applicant.
[0321] Advantageously, although not necessarily, the tracer device is arranged (along the section PA) downstream (in the direction A) of the compression station 11 ^{* .}
[0323] With particular reference to Figures 35 and 36, according to some non-limiting embodiments, the plant 1 (more precisely, the feeding device 9) comprises a regulation device 45 that is arranged (along the section PA) upstream (in direction A) of the compaction device 3 and is configured to regulate the width of the first powder FP (in particular, of the first zone FZ) in the conveyor group 5 (in particular, in the compression belt 34; in particular, in the plane of transport).
[0325] Advantageously, although not necessarily, the regulation device 45 comprises two moving belts 46 arranged on opposite sides of the first powder FP (of the first zone FZ) and a movement device (of a type known per se and not illustrated) to vary the relative inclination of the two belts.
[0327] According to some specific non-limiting embodiments, in use, the feeding device places the first and second parts FFP and SFP of the first powder FP simultaneously on the belt 34 (of the conveyor group 5 - see, for example, Figure 5 and left part of Figure 7) with the first thickness corresponding to height H.
[0329] At this point (see Figure 8 and slightly to the right in Figure 7), the compression device 11 exerts a pressure on the first powder FP (towards the belt 34) to reduce its thickness to the second thickness corresponding to the height HH .
[0330] Subsequently (Figure 9 and central part of Figure 7), the feeding device 10 carries (by fall) the second powder SP on the part of the conveyor group 5 (more precisely, of the belt 34) not occupied by the first powder FP .
[0332] Thanks to the movement of the conveyor group 5, the powder material CP (composed of the first powder FP and the second powder SP) is then fed (Figure 10 and right part of Figure 7) to the work station 4, where it is compacted (central part of Figure 1) by compaction device 3 in order to further reduce its thickness (fourth thickness, corresponding to height HHH), reach a density of approximately 1.8-2.2 kg/dm3 and obtain the layer of compacted powder KP.
[0334] The compacted powder layer KP, at this point, is cut, decorated and sintered to get slabs 30.
[0336] Advantageously, although not necessarily, plant 1 is configured to implement the method described below.
[0338] According to another aspect of the present invention, a method of manufacturing ceramic articles T.
[0340] In particular, the method is implemented by the plant 1 described above.
[0342] The method comprises a compaction step, during which a powder material CP comprising ceramic powder is compacted in correspondence with a work station 4 to obtain a layer of compacted powder KP; a transport step, during which the powder material CP is transported (in particular substantially continuously) by a conveyor group 5 along a first section PA of a given path (in a forward direction A) from an input station 6 to the work station 4 and the compacted powder layer KP is transported by the conveyor group 5 along a second section PB of the determined path from the work station 4 to an output station 7; and a feeding step, during which the powder material CP is fed onto (in the zone CZ of) the conveyor group 5 (the powder material CP is fed onto the conveyor group 5 to directly come into direct contact with the group conveyor 5) in correspondence with the input station 6 by means of a feeding group 8.
[0344] In particular, the transport stage and the feeding stage are (at least partially) simultaneous. Additionally or alternatively, the compaction step and the transport step are (at least partially) simultaneous. Additionally or alternatively, the compaction step and the feeding step are (at least partially) simultaneous.
[0346] According to non-limiting embodiments, during the compaction step, a pressure of at least about 350 kg/cm2 (in particular, at least 380 kg/cm2; in particular, up to 450 kg/cm2; more in particular, up to 420 kg/cm2) on the CP powder material.
[0348] In some non-limiting cases, the layer of compacted powder KP has an (apparent) density of at least about 1.8 kg/dm3 (in particular, at minus about 1.9 kg/dm3; in particular, up to about 2.2 kg/dm3; more particularly, up to about 2.1 kg/dm3).
[0350] Advantageously, although not necessarily, the CP powder material comprises a first (micronized) FP powder predominantly made up of particles having sizes less than about 180 µm, in particular greater than about 30 µm. In particular, the first FP powder is as defined above (in relation to plant 1). More particularly, the CP powder material is as defined above (in relation to plant 1).
[0352] It has been experimentally observed that the ceramic articles T obtained using this type of powder surprisingly present more defined zones and, in the case where the powders have different colours, more precise and natural aesthetic effects.
[0354] In particular, during the feeding step, the first powder FP is fed to the conveyor group 5 to come into contact with the conveyor group 5.
[0356] Advantageously, although not necessarily, the powder material CP comprises a second powder SP (micronized) predominantly made up of particles having sizes greater than about 200 µm, in particular less than about 600 µm. In particular, the second powder SP is as defined above (in relation to plant 1).
[0358] By using the second powder SP (in combination with the first powder FP) it was possible to simplify the procedure and reduce the production costs. In fact, SP powder has a lower cost (easier to produce) and has proven to be easy to handle (being easier to transport in mass - it requires ducts with passage sections significantly smaller than those for micronized powders). ).
[0360] In this regard, it should be noted that it is known that in order to produce (ceramic-sprayed) powder having the characteristics of the second powder SP, an atomisation process is generally used which involves spraying slip towards a stream of hot air. The slip solidifies on contact with hot air into particles having the sizes indicated above (and in particular also the angle of repose indicated above).
[0361] The first FP powder (or powder having its characteristics - micronized powder), on the other hand, is generally obtained from atomized particles (like those of the second SP powder) which are further treated by means of a pin mill.
[0363] The different type of production process implies different characteristics in the powders.
[0365] The second powder SP has an apparent density (ratio of mass to volume occupied without compressing the powder) usually around 0.8-1.2 kg/dm3 (typically between about 0.95 and about 1.05 kg/dm3) .
[0367] The first powder FP has an apparent density (ratio of mass to volume occupied without compressing the powder) different (lower) than that of the second powder SP and normally around 0.65-0.70 kg/dm3, much lower than the bulk density of the second powder SP (typically between about 0.95 and about 1.05 kg/dm3).
[0369] It has been experimentally observed that by imposing a different compaction ratio (ratio between final density and initial density) between the two materials, ceramic products T and the compacted powder layer KP are surprisingly obtained in the act of pressing (with reduced internal stresses). More precisely, though not necessarily, the first powder compaction ratio FP and the second powder compaction ratio SP (and thus the first, second, third and fourth thicknesses) are selected such that (are such that ) the densities of the first powder FP and the second powder SP after the compaction step have a difference of less than 0.05 kg/dm3 (in particular, less than or equal to 0.03 kg/dm3; more in particular, less than or equal to 0.02 kg/dm3, even more particularly, are substantially the same).
[0371] According to some non-limiting embodiments, given the target value (to be obtained) of gross density (density of the compacted powder layer KP) of approximately 2.00 kg/dm3 (with a compaction pressure of approximately 400 kg/ cm2), the compaction ratio is about 2.0-2.1 for the second powder SP and 2.85-3.0 for the first powder FP.
[0373] As already indicated above, the comparison between Figures 6 and 3 (and between Figures 2 and 4) shows the different behavior of the spray-dried powders in a low angle of repose (Figures 6 and 2) and the first micronized FP powder, which advantageously, although not limited to, has a high angle of repose.
[0374] According to some non-limiting embodiments (Figure 7), the feeding stage comprises a first feeding sub-stage, during which the first FP powder is fed onto (in direct contact with) a first part (of the mentioned CZ zone) of the conveyor group 5 by means of a feeding device 9 of the feeding group 8 to present a first thickness (ie a height with respect to the conveyor group); and a second feeding substep, during which the second powder SP is fed onto (in direct contact with) a second part different from the first mentioned part (of said zone CZ) of the conveyor group 5 by a feeding device 10 of said feeding group 8.
[0376] Advantageously, although not necessarily, the method further comprises a compression step (Figure 8), which takes place in a compression station 11* upstream (with respect to the forward direction A), in particular along the first section PA, of the work station 4 and during which the first powder FP arranged in said conveyor group 5 is compressed to present a second thickness less than the first thickness.
[0378] It has been experimentally observed that in this way the stresses in the ceramic articles T are surprisingly reduced. It has been hypothesized that this is due to the fact that in this way the bulk densities of the first powder FP and the second powder SP approach each other.
[0380] According to some non-limiting embodiments, during the second feeding sub-stage (FIG. 9), the second powder SP is fed to the conveyor group 5 to present a third thickness less than the first thickness, in particular substantially equal to the second thickness.
[0382] It should be noted that, advantageously although not necessarily, the first thickness and the second thickness (and therefore the third thickness) are selected such that, after the compression step and the compaction step, the apparent density of the first powder FP is similar to the bulk density of the second powder SP (in particular, between 1.8 and 2.2 kg/dm3; more precisely, as indicated above with respect to the bulk density of the layer of compacted powder KP).
[0383] Also in this case, it has been experimentally observed that it is surprisingly possible to obtain particularly solid ceramic articles T (with particularly low internal stresses).
[0385] According to specific non-limiting embodiments, the first thickness (corresponding -equal- to a height H), the second thickness (corresponding -equal- to a height HH), the third thickness (corresponding -equal- to the height HH) and the fourth thickness (corresponding - equal - to a height HHH) are selected so that the following relation is satisfied:
[0387] D1 = D2 ± 0.030 kg/dm3 (preferably, but not necessarily, D1 = D2 ± 0.020 kg/dm3)
[0389] where
[0391] D1 = HH/HHH x SD
[0393] D2 = H/HHH x DF
[0395] where DS is the apparent density of the second powder SP; DF is the bulk density of the first FP powder.
[0397] Advantageously, although not necessarily (always in this context), the compaction ratio applied to the first FP powder after the compression step and the compaction step is from about 2.60 to about 3.2 (in particular, from about 2 .75 to about 3.1). In addition or alternatively, the compaction ratio applied to the second SP powder after the compaction step is from about 1.7 to about 2.4 (particularly from about 1.9 to about 2.2).
[0399] By compaction ratio is meant the ratio between the density (of the first and/or second FP and SP powders) after and before the compaction and possibly compression stage.
[0401] According to some non-limiting embodiments, at least a part of the first FP powder has a first color. In particular, the particles of the first powder FP have (are) predominantly (of) a first color.
[0403] Advantageously, although not necessarily, the particles of the second powder SP have (are) predominantly (of) a second color (eg white) different from the first color (eg black).
[0405] According to some non-limiting embodiments, during the feeding stage, the layer of powder material CP is obtained, which has at least one first zone FZ with a predominant content of the first powder FP and at least one second zone SZ with a predominant content of of the second powder SP.
[0407] Advantageously, but not necessarily, the powder layer CP has a third zone TZ, which is arranged between the first zone FZ and the second zone SZ of the powder layer CP and has a predominant content of (in particular, is constituted by the) first powder FP. In these cases, in particular, the particles of the second powder SP and the particles of the first powder FP of the third zone TZ of the powder layer CP predominantly have a (same) second color different from the first color of the first powder FP of the first zone FZ.
[0408] In this way, it has been experimentally observed that the definition of the particle distribution of the first powder FP of the first zone FZ has been surprisingly increased even more. It has been hypothesized that this is due to the fact that it becomes more difficult for larger (and therefore visible) agglomerates of the second powder SP to mix with the particles of the first powder FP in the first zone FZ.
[0410] According to some non-limiting embodiments (such as the one illustrated), the first feeding sub-stage takes place in correspondence with a feeding station 22 upstream (with respect to the forward direction A), in particular along the first section PA, of a feeding station 23, in correspondence with which the second feeding sub-step takes place. In these cases, in particular, the compression station 11* is arranged (along the first section PA) between the feeding station 22 and the second feeding station 23.
[0412] Advantageously, although not necessarily, the feeding device 9 in turn comprises at least two lateral unloading units 12 and at least one central unloading unit 13. In particular, the central unloading unit 13 is arranged between the two unloading units. side 12. During the feeding stage, the central discharge unit 13 carries a first FFP part of a first FP powder onto the conveyor group 5 and each side discharge unit 12 disposes a respective second SFP part of the first FP powder on the conveyor group 5 at the sides and in contact with the first FFP part of the first FP powder, so that the second SFP parts of the first FP powder laterally support and limit the movements of the first FFP part of the first FP powder.
[0414] Surprisingly, a further improvement in the positioning accuracy of the first powder FP (which is supported laterally and thus further reduces the possibility of flashing) is thus surprisingly obtained.
[0416] In particular, it should be noted that the first part FFP defines the first zone FZ of the powder material layer CP (thus, the particles of the first part FFP are of the same type - they are the same - and are defined as those of the first zone FZ). In addition or alternatively, the second part SFP defines the third zone TZ of the powder layer CP (therefore, the particles of the second part SFP are of the same type - they are the same - and are defined as those of the third part). TZ zone).
[0418] According to some non-limiting embodiments, the lateral discharge units 12 and the central discharge unit 13 (are substantially integral with each other and) are substantially aligned with each other (during the feeding step) in an alignment direction B (in particular , transverse to direction A).
[0420] More precisely, although not necessarily, during the feeding stage, the side discharge units 12 and the central discharge unit 13 are rotated (to change the orientation of the relative position of the side discharge units 12 and the central discharge unit). center 13).
[0422] More particularly, the side discharge units 12 and the center discharge unit 13 are rotated to modify the alignment direction B. In particular, the lateral discharge units 12 and the central discharge unit 13 rotate around an axis AA substantially perpendicular to the direction A. In particular, the axis AA is substantially perpendicular to the aforementioned transport plane (in which the the first FP powder and fed to the outlet station).
[0424] According to some non-limiting embodiments, the axis AA passes through the central discharge unit 13 (more precisely, through its center).
[0426] In particular, the first part of the conveyor group 5 on which it is fed (in particular, is deposited) the first powder FP, presents a position on the conveyor group 5.
[0428] Advantageously, although not necessarily, during the first feeding sub-stage, the position of the first part (of the mentioned CZ zone) of the conveyor group 5 is modified (moved) to carry out the distribution (in a certain way) of the first powder FP in the conveyor group 5. In particular, the position of the first part (of the mentioned zone CZ) of the conveyor group 5 moves in a direction C transverse (more in particular, perpendicular) to the direction A of advance (in which the conveyor group 5 transports the powder material CP along the first section PA towards the work station 4).
[0430] In addition or alternatively, during the feeding stage (in particular during the first feeding sub-stage) a movement unit 17 moves the feeding device 9 (in particular in the direction C transverse to the forward direction A) so that the feeding device 9 can carry out the distribution (in a certain way) of the first powder FP in the conveyor group 5, in particular in the mentioned transport plane.
[0432] According to some non-limiting embodiments, the first FFP part and the second SFP part of the first FP powder are (both) micronized powders (predominantly made up of particles having sizes less than about 180 µm, in particular greater than about 30 µm). ).
[0434] With particular reference to Figures 20-25, advantageously, although not necessarily, the first part FFP is a micronized powder (predominantly made up of particles having sizes less than about 180 µm, in particular greater than about 30 µm); and the second SFP part is an atomized powder (predominantly made up of particles having sizes greater than 200 μm, in particular less than 600 μm).
[0436] In these cases, in particular, the first part FFP of the first powder FP that is deposited on the conveyor group 5 (more precisely, on the belt 34; more precisely, on the transport plane) by the central discharge unit 13 itself presents substantially the first thickness (of height H - in the conveyor group 5); and the second part SFP of the first FFP powder deposited on the conveyor group 5 (more precisely, on the belt 34; more precisely, on the transport plane) by the side unloading units 12 themselves presents substantially the second thickness (or third thickness - of height HH - in the conveyor group 5).
[0438] In these cases, during the compression stage only the first FFP part is compressed. In other words, more precisely, the second part SFP can be considered to be comprised in the second powder SP.
[0440] With particular reference to Figures 26-31, advantageously, although not necessarily, the first part FFP is an atomized powder (predominantly made up of particles having sizes greater than 200 µm, in particular less than 600 µm); and the second SFP part is a micronized powder (predominantly made up of particles having sizes less than about 180 µm, in particular greater than about 30 µm).
[0442] In these cases, in particular, the first part FFP of the first powder FP that is deposited on the conveyor group 5 (more precisely, on the belt 34; more precisely, on the transport plane) by the central discharge unit 13 itself presents substantially the second thickness (or third thickness - of height HH - in the conveyor group 5); and the second part SFP of the first FFP powder deposited on the conveyor group 5 (more precisely, on the belt 34; more precisely, on the transport plane) by the lateral discharge units 12 themselves, substantially presents the first thickness (of height H - in the conveyor group 5).
[0444] In these cases, only the second SFP part is compressed during the compression stage. In other words, more precisely, the first part FFP can be considered to be comprised in the second powder SP.
[0446] According to some non-limiting embodiments, both the first part FFP and the second part SFP of the first powder FP are fed (along the section PA) upstream of the compression station 11*.
[0448] Advantageously but not necessarily (Figures 20-22), the second SFP part is fed to (on) the conveyor group 5 (in particular, on the belt 34; in particular, on the transport plane) downstream (in the direction A ) of the compression station 11*.
[0449] In these cases, during the compression stage only the first FFP part is compressed. In other words, more precisely, the second part SFP can be considered to be comprised in the second powder SP.
[0451] Advantageously but not necessarily (Figures 29-31), the first FFP part is fed to (on) the conveyor group 5 (in particular, on the belt 34; in particular, on the transport plane) downstream (in the direction A ) of the compression station 11*.
[0453] In these cases, only the second SFP part is compressed during the compression stage. In other words, more precisely, the first part FFP can be considered to be comprised in the second powder SP.
[0455] Advantageously, although not necessarily, the method comprises a printing step, which is subsequent to the compaction step and during which a graphic decoration is made on (over) the layer of compacted ceramic powder KP transported by the conveyor group 5 in correspondence with a printing station 19 along the determined path downstream of the work station 4. In particular, a control unit 20 controls the printing step to perform graphic decoration coordinated with the distribution of the first FP powder in the group transporter 5.
[0457] Advantageously, although not necessarily, the method comprises an extraction step, during which a superficial part of the powder material CP arranged on the conveyor group 5 is removed (in particular, by suction) in correspondence with an extraction station 27 arranged downstream. below (with respect to the direction of advance A), in particular along the first section PA, of the input station 6 (more precisely, of the feeding stations 22 and 23).
[0459] According to some non-limiting embodiments, the method comprises a cutting step, during which the compacted powder layer KP is cut to obtain the slabs 30.
[0461] In particular, the method comprises a firing step to sinter the compacted powder layer KP of the slabs 30 to obtain the ceramic articles T; in particular, the firing stage is carried out by means of a firing furnace 33 arranged along the path determined downstream of the printing station 19.
[0463] Unless explicitly stated otherwise, all references (articles, books, patent applications, etc.) cited in this text are alluded to. In particular, the references mentioned are incorporated herein by reference.

权利要求:
Claims (10)
[1]
1. Plant for the manufacture of ceramic articles (T), the plant (1) comprising a compaction machine (2) for compacting a powder material (CP) comprising ceramic powder;
the compaction machine (2) comprising a compaction device (3), which is arranged in correspondence with a work station (4) and is configured to compact the powder material (CP) to obtain a layer of compacted powder (KP ); a conveyor group (5) to transport the powder material (CP) along a first section (PA) of a given path from an input station (6) to the work station (4) and the powder layer compacted (KP) along a second section (PB) of the path determined from the work station (4) to an output station (7); and a feeding group (8), which is configured to feed the powder material (CP) to the conveyor group (5) in correspondence with the input station (6);
the plant (1) being characterized in that the feeding group (8) comprises a first feeding device (9), which is configured to feed a first powder (FP) to the conveyor group (5); the first feeding device (9) in turn comprises at least two side discharge units (12) and at least one central discharge unit (13), which is configured to carry a first part (FFP) of a first powder ( FP) on the carrier group (5);
each side discharge unit 12 being configured to dispose a respective second part (SFP) of the first powder (FP) on the conveyor group (5) at the sides and in contact with the first part (FFP) of the first powder (FP), so that the second parts (SFP) of the first powder (FP) laterally support and limit the movements of the first part (FFP) of the first powder (FP);
the central discharge unit (13) being arranged between said at least two lateral discharge units (12); the side discharge units (12) and the central discharge unit (13) being substantially aligned with each other in an alignment direction (B); the feed unit (8) comprising a rotation unit (16) which is configured to rotate the side discharge units (12) and the central discharge unit (13) to modify the alignment direction (B).
[2]
Plant according to claim 1, wherein said rotation unit (16) is configured to rotate the lateral discharge units (12) and the central discharge unit (13) around an axis (AA) substantially perpendicular to a transport plane of the conveyor group (5).
[3]
Plant according to claim 1 or 2, in which the feeding group (8) comprises a movement unit (17) that is adapted to move the first feeding device (9) (in particular in a direction transverse to a direction (A) of advance in which the transport group (5) transports the first powder (FP) towards the second feeding device (10)) so that the first feeding device (9) can carry out a distribution of the first powder (FP) on the transport group (5), in particular on said transport plane.
[4]
Plant according to any of the preceding claims, in which the first feeding device (9) is configured to feed the first powder (FP) to the conveyor group (5) such that the first powder (FP) substantially has a first thickness on the conveyor group (5); the central discharge unit (13) presenting an outlet mouth (14) directed towards the conveyor group (5) and separated from the conveyor group (5) by a height (H) substantially equal to said first thickness; each lateral discharge unit (12) presenting a respective outlet mouth (15) directed towards the conveyor group (5) and separated from the conveyor group (5) by a height (H) substantially equal to said first thickness.
[5]
5. Plant according to claim 4, in which the first feeding device (9) is arranged along the first section (PA) and is configured to feed the first powder (FP) predominantly made up of particles with sizes smaller than 180 µm (in particular, greater than 30 µm) to the conveyor group (5) in a first part of the conveyor group (5);
the plant (1) also comprising a second feeding device (10), which is arranged along the first section (PA) and is configured to feed a second powder (SP) predominantly made up of particles having sizes greater than 200 ^m (in particular less than 600 ^m) on a second part of the conveyor group (5) different from said first part of the conveyor group (5); and a compression device (11), which is arranged in correspondence with a compression station (11*) along the first section (PA) upstream of the work station (4) and downstream of the first feeding device (9) and is configured to compress the first powder (FP) so that the first powder (FP) has a second lower thickness at the first thickness.
[6]
Plant according to claim 5, in which the first feeding device (9) is arranged upstream of the second feeding device (10); the compression device (11) is arranged between the first feeding device (9) and the second feeding device (10); in particular, the second feeding device (10) is configured to feed the second powder (SP) to the conveyor group (5) so that the second powder (SP) has a third thickness in the conveyor group (5); the third thickness being substantially equal to the second thickness.
[7]
7. Method for the manufacture of ceramic articles (T), the method comprising:
a compaction step, during which a powder material (CP) comprising ceramic powder is compacted in a work station (4) to obtain a layer of compacted powder (KP);
a transport step, during which the powder material (CP) is transported (in particular substantially continuously) by a conveyor group (5) along a first section (PA) of a given path from a station input (6) to the work station (4) and the layer of compacted powder (KP) is transported by the conveyor group (5) along a second section (PB) of the path determined from the work station ( 4) to a departure station (7);
a feeding stage, during which the powder material (CP) is fed to the conveyor group (5) in correspondence with the input station (6) by a feeding group (8); in particular, the transport stage and the feeding stage are at least partially simultaneous;
the method being characterized in that the powder material (CP) comprises a first powder (FP); during the feeding step, a first feeding device (9) of the feeding group (8) feeds the first powder (FP) to the conveyor group (5); the first feeding device (9) in turn comprises at least two side discharge units (12) and at least one discharge unit middle (13);
During the feeding stage, the central discharge unit (13) carries a first part (FFP) of a first powder (FP) on the conveyor group (5) and each lateral discharge unit (12) has a second part (SFP). ) of the first powder (FP) on the conveyor group (5) on the sides and in contact with the first part (FFP) of the first powder (FP), so that the second parts (SFP) of the first powder (FP) laterally support and limit the movements of the first part (FFP) of the first powder (FP);
the central discharge unit (13) being arranged between said at least two lateral discharge units (12); the side discharge units (12) and the central discharge unit (13) being substantially aligned with each other in an alignment direction (B); the lateral discharge units (12) and the central discharge unit (13) being rotated during the feeding step to modify the alignment direction (B).
[8]
Method according to claim 7, in which the lateral discharge units (12) and the central discharge unit (13) rotate around an axis (AA) substantially perpendicular to a transport plane, on which the first lies. powder and is fed by the conveyor group (5) to the outlet station (7); in particular, said axis (AA) is substantially perpendicular to said direction (A) of advance.
[9]
Method according to claim 7 or 8, in which, during the feeding step (in particular during the first feeding sub-step) a movement unit (17) moves the first feeding device (9) (in particular, in a direction transverse to a direction (A) of advance in which the conveyor group (5) transports the first powder (FP) towards the work station (4)) so that the first feeding device (9) can perform a distribution of the first powder (FP) on said conveyor group (5), in particular on said transport plane.
[10]
Method according to any of claims 7 to 9, in which during the feeding step a layer of powder material (CP) is obtained, which has at least one first zone (FZ) with a predominant content of the first powder ( FP) and at least one second zone (SZ) with a predominant content of a second powder (SP); the first powder (FP) being predominantly made up of particles with sizes less than 180 μm, in particular greater than 30 μm; the second powder (SP) being predominantly made up of particles with sizes greater than 200 μm, in particular less than 600 μm; in particular, the first powder (FP) having an angle of repose greater than 55°, in particular greater than 65° (in particular less than 90°); in particular, the second powder (SP) having an angle of repose of less than 45° (in particular, greater than 20°).

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