Compaction device for compacting ceramic powder material

Abstract

A compaction device (1) for compacting a layer (2) of ceramic powder material comprising : a transport surface (4) to receive and advance the layer (2) along an advance direction (A); a belt compaction element (5), which defines, with a lower branch thereof, a compaction surface (8) facing the transport surface (4); a first pressing roller (13), which cooperates with the transport surface (4); a second pressing roller (14), which is parallel to and is placed above the first pressing roller (13) and is designed to press the compaction surface (8) towards the transport surface (4) so as to compact the layer (2) of powder material; a countering element (21); and a moving system (22) to move the countering element (21) so as to adj ust the inclination of the compaction surface (8) relative to said advance direction (A).

Description

[0001] COMPACTION DEVICE FOR COMPACTING CERAMIC POWDER MATERIAL

[0002] Cross-Reference to Related Applications

[0003] This Patent Appl ication claims priority from Italian Patent Application No . 102024000002782 filed on February 9 , 2024 , the entire disclosure of which is incorporated herein by reference .

[0004] Technical Field

[0005] The invention relates to a compaction device for compacting powder material ; in particular, to a compaction device of ceramic powder material ; namely, to a compaction device of powder material comprising ceramic powder .

[0006] Background of the Invention

[0007] In the ceramic processing industry, systems are known, which are used to manufacture ceramic products , such as ceramic slabs or tiles , and compri se : a transport assembly, which defines a transport surface ; a ceramic powder feeding system, which is designed to progressively feed a (namely, a defined quantity of ) ceramic powder material onto the transport assembly, in particular onto the transport surface , so as to form a layer of ceramic powder .

[0008] The layer of ceramic powder is caused to advance by the transport surface through a continuous compaction station, which is designed to compact the powder layer as it advances on the transport surface , so as to form a continuous strip of compacted ceramic powder .

[0009] Downstream of the compaction station there generally are further known processing stations , for example at least one cutting station, where the continuous strip of compacted ceramic powder is divided into single slabs or tiles , and further decoration and / or finishing stations .

[0010] Known compaction devices typically comprise two flexible compaction surfaces , one above the other, and both capable of sliding in the same direction so as to lock the layer of ceramic powder between one another and press it as it advances through the compaction station .

[0011] In particular, the lower compaction station is generally arranged directly in contact with the transport surface so as support it or coincides with the transport surface ; whereas the upper compaction surface is arranged parallel to and at a given distance (namely, height ) from the transport surface so that a gap is defined between, which is designed to receive the layer of ceramic powder to be compacted .

[0012] Each compaction surface is usually defined by a respective flexible, sliding belt , typically made o f steel , which is wound around a plurality of rollers with a hori zontal axis , typically a motori zed roller, a pulley and a pressing roller .

[0013] More in detail , the compaction device generally comprises a pair of pressing rollers on top of one another, which, in a predetermined compaction zone , are designed to guide the compaction surfaces so as to hold the upper compaction surface locally pressed towards the lower compaction surface so as to press the powder layer transported by the transporting belt and form the aforesaid strip of compacted ceramic powder .

[0014] In the ceramic processing industry, the correct configuration and the mutual arrangement of the compaction surfaces in the zone immediately upstream of the aforesaid predetermined compaction zone are essential to make sure that the ceramic powder is properly fed between the pressing rollers and to reduce the risk that undesired air remains trapped in the ceramic powder and / or that other irregularities in the feeding of the ceramic powder arise , for example small lumps of ceramic powder, which could cause defects and / or irregularities during the pressing step or in the following processing steps , which, in most serious cases , could cause the ceramic product to be rej ected . These phenomena are linked to undesired deformations of the upper compaction surface in the zone upstream of the predetermined compaction zone along the advance direction, when the ceramic powder is fed between the two pres sing rollers . As a matter of fact , the layer of ceramic powder can induce a deformation of the belt forming the upper compaction surface , in other words a inward bend of the steel belt constituting the upper compaction surface , as the powder material is fed towards the predetermined compaction zone ( as schematically shown with a broken line in figure 7 ) .

[0015] In particular, experiments have shown that , in order to avoid these risks , the upper compaction surface needs to be and remain, in use (hence , even upon feeding of the ceramic powder between the two pressing rollers ) , parallel to the transport surface or inclined upwards relative to the transport surface , so as to progres sively reduce the distance between the upper compaction surface and the transport surface , moving from the predetermined compaction zone towards an upstream zone along the material feeding direction .

[0016] To this very aim, the applicant provided, in some of the known compaction devices , two auxiliary devices , speci fically at least two auxiliary rollers with hori zontal axes , which are parallel to the pressing rollers , are located upstream of the pressing rollers relative to the advance direction of the layer of powder material and are designed to guide and hold in position the pressing belts that define the upper compaction surface and the lower compaction surface , respectively . An example of such known machines is described in the document EP1674228A2 of the same applicant of the present application .

[0017] In particular, in the known machines , the lower auxiliary roller is located upstream of the lower pressing roller, on a plane parallel to the advance direction, and is in contact with the steel belt of the lower compaction device so as to maintain the planar character of the transport surface and of the lower compaction surface . On the other hand, the upper auxiliary roller i s located upstream of the upper pressing roller and is designed to act upon the pressing belt forming the upper compaction surface in order to hold it in the right position, thus minimi zing the risk of deformations or at least the extent of the deformation of said belt upon feeding of the ceramic powder between the two pressing rollers .

[0018] However, these compaction devices suf fer from some drawbacks .

[0019] Indeed, said known compaction devices , in order to be suited for the formation of di f ferent types of ceramic products having a di f ferent thickness , of fer the possibility of adj usting the mutual distance between the pressing rollers , typically by adj usting the height of the upper pressing roller . Such movement of the upper pressing roller, in particular when it is used to reduce its from the lower pressing roller, inevitably leads to a movement of the pressing belt forming the upper compaction surface , which inevitably makes , at least in some operating configurations , the upper auxiliary roller (when present ) completely inef fective .

[0020] This leads , at least in these operating configurations , to an unavoidable bending ( curvature ) of the upper compacting belt , with all the above-mentioned risks connected thereto .

[0021] The obj ect of the invention is to provide a compaction device for compacting ceramic powder material , which at least partly solves the problems caused by prior art devices .

[0022] Summary

[0023] According to the invention, there is provided a compaction device for compacting ceramic powder material according to the independent claims attached thereto and, preferably, according to any one of the dependent claims directly or indirectly depending on the aforesaid independent claims .

[0024] The appended claims describe pre ferred embodiments of the invention and form an integral part of the description .

[0025] Brief Description of the Drawings

[0026] The invention wi ll now be described with reference to the accompanying drawings , which show some non-limiting embodiments thereof , wherein : figure 1 is a front view of a compaction device according to an embodiment of the invention;

[0027] - figure 2 shows a vertical section view along section

[0028] I I- I I of the compaction device of figure 1 ; figure 2A is an enlarged scale view of the part contained in the frame indicated with W in figure 2 ;

[0029] - figure 3 shows a section view along section I I I - I I I of the device of figure 1 ;

[0030] - figures 3A and 3B are enlarged scale views of the parts contained in the frames indicated with TA and TB, respectively, in figure 3 ;

[0031] - figure 4 is a front view of the compaction device of figure 1 , in a di f ferent operating configuration, in which it can be used to manufacture ceramic articles having a greater thickness ;

[0032] - figure 5 shows a vertical section view along section V-V of the compaction device of figure 4 ;

[0033] - figure 5A is a view on a larger scale of the part of the device contained in the frame indicated with Z ; figure 6 is a perspective view of part of the compaction device of figures 1 and 4 according to an embodiment of the invention;

[0034] - figure 7 is a schematic side view of part of a known compaction device , which shows : an upper belt compaction element , a transport surface , on which a layer of powder material advances , and - with a broken line - the possible deformation of the upper pressing belt following the feeding of the layer of powder material in the compaction zone ; figure 8 is a schematic side view of part of a compaction device according to a first embodiment of the invention, which schematically shows an upper belt compaction element , a transport surface , on which a layer of powder material advances , and a countering element in the form of a pre-roller, which acts upon the upper pressing belt to avoid, or at least to limit , the deformation thereof ;

[0035] - figure 8A is a schematic side view of part of a compaction device according to a second embodiment of the invention, which schematically shows an upper belt compaction element , a transport surface , on which a layer of powder material advances , and a countering element in the form of a pad with a curved contact surface , which acts upon the upper pressing belt to avoid, or at least to limit , the deformation thereof ;

[0036] - figure 8B is a schematic side view of part of a compaction device according to a further embodiment of the invention, which schematically shows an upper belt compaction element , a transport surface , on which a layer of powder material advances , and a countering element in the form of a pad with a substantially flat contact surface , which acts upon the upper pressing belt to avoid or at least limit the deformation thereof ;

[0037] - figure 8C is a schematic side view of part of a compaction device according to yet another embodiment of the invention, which schematically shows an upper belt compaction element , a transport surface , on which a layer of powder material advances , and a countering element consisting of a series of rollers , which acts upon the upper pressing belt to avoid, or at least to limit , the deformation thereof ;

[0038] - figure 9 shows a vertical section view along section IX- IX of the compaction device of figure 1 ;

[0039] - figure 10 is a side view of the compaction device of figure 1 ;

[0040] - figure 11 shows a vertical section view along section XI-XI of the compaction device of figure 4; and

[0041] - figure 12 is a side view of the compaction device of figure 4.

[0042] Detailed Description

[0043] In the attached figures, reference number 1 indicates, as a whole, a compaction device for compacting powder material; in particular, a compaction device of powder material comprising ceramic powder; more in particular, a compaction device of a layer 2 of powder material (schematically shown in figures 7 and 8) comprising ceramic powder .

[0044] The compaction device 1 can advantageously be used in a plant for manufacturing ceramic tiles or slabs (not shown in the accompanying figures and of the known kind) .

[0045] It should be pointed out that, in this description, terms such as "upper", "lower", "side", "right", "left" or "height" are used with reference to the compaction device 1 resting on a horizontal plane, for instance resting on the ground or on a floor (as shown, for example, in figures 1 and 4) , so that, for example, the term "at the top" or "at the bottom" means "located above" or "located under", respectively, relative to another component of the compaction device 1, when the compaction device 1 rests on the floor or on the ground, namely "located farther from" or "located closer to" the horizontal plane, hence the floor or the ground, on which the compaction device 1 rests. Similarly, "internally" and "externally" mean "on the inside" and "on the outside" of the compaction device 1. Furthermore, for the purposes of the invention, the term "second" component does not imply the presence of a "first" component . As a matter of fact , these terms are only used as labels to improve clarity and should not be interpreted in a limiting manner .

[0046] With special reference to the accompanying figures , the compaction device 1 advantageously comprises : a frame 3 ; a transport surface 4 , which advantageously but not in a limiting manner i s carried by the frame 3 , is configured to receive and advance the layer 2 of powder material comprising ceramic powder in an advance direction A; and an upper belt compaction element 5 , which, advantageously, but not in a limiting manner, is carried by the frame 3 and, in turn, comprises a plurality of rollers 6a, 6b with a hori zontal axis (namely, each having a respective hori zontal rotation axis perpendicular to the advance direction A) , among which there are ( in particular, comprising) at least one motorized roller 6a and a pulley 6b, and an upper pressing belt 7 wound around said plurality of rollers 6a, 6b so as to define , with a lower branch thereof , an upper compaction surface 8 , which substantially faces the transport surface 4 and is movable along the advance direction A.

[0047] With special reference to the accompanying figures , the transport surface 4 is configured to receive and advance the layer 2 of powder material compris ing ceramic powder in the advance direction A from a feeding station (not visible in the accompanying figures ) , where powder material ( in particular, a measured quantity of powder material ) comprising ceramic powder is fed onto the transport surface 4 as the latter advances in the advance direction so as to form the layer 2 of powder material comprising ceramic powder, up to an output station 9 , where a continuous strip figures 7 , 8 , 8A, 8B and 8C ) is released by the compaction device 1 , advantageously but not limitatively , towards further processing stations (not shown and of the known kind) , going through at least one predetermined compaction zone 11 , where the layer 2 of powder material is compacted, and an invitation zone 12 , immediately upstream of the predetermined compaction zone 11 .

[0048] Furthermore , the compaction device 1 advantageously comprises : a lower pressing roller 13 , which has a hori zontal rotation axis (namely, perpendicular to the advance direction A and parallel to the transport surface 4 ) and is located under the transport surface 4 ; and an upper pressing roller 14 , which is parallel to and located above the lower pressing roller 13 and cooperates with the upper compaction surface 8 ( in particular, with the pressing belt 7 forming said compaction surface 8 ) in order to press the upper compaction surface 8 towards the transport surface 4 at the predetermined compaction zone 11 so as to compact the layer 2 of powder material and form the aforesaid compacted continuous strip 10 of ceramic powder material .

[0049] Advantageously but not in a limiting manner, in use , the lower pressing roller 13 and the upper pressing roller 14 are configured to keep the upper compaction surface 8 locally pressed towards the transport surface 4 , so as to compress the layer 2 of powder material interposed between them .

[0050] More advantageously, though not in a limiting manner, the upper pressing roller 14 is configured to press the upper compaction surface 8 towards the transport surface 4 so that a gap with a defined thickness remains between them, at predetermined compaction zone 11 , to form the aforesaid compacted continuous strip 10 of ceramic powder material .

[0051] It should be pointed out that "thickness of the gap" indicates the extension thereof perpendicularly to the surfaces delimiting it , in this speci fic case , indicates the distance between the upper compaction surface 8 and the transport surface 4 ( or, when available , as explained more in detail below, the lower compaction surface 16 ) at the predetermined compaction zone 11 . In other words , "defined thickness" means extension (namely, dimension) of the gap along the vertical direction, namely perpendicularly to the transport surface 4 ( see figures 2A and 5A) .

[0052] According to some advantageous though non-limiting embodiments , such as for example the ones shown in the accompanying figures , the compaction device 1 comprises a further lower belt compaction element 17 , which, in turn, comprises a further plurality of rollers 18 with a hori zontal axis , among which there are ( in particular, comprising) at least one motori zed roller 18 and one or more idle rollers (not visible in the accompanying figures ) , and a further belt 19 wound around said plurality of rollers 18 and configured to define , with the upper branch thereof , a further lower compaction surface 20 located under the transport surface 4 . More advantageously, though not in a limiting manner, the lower compaction surface 20 is in direct contact with the transport surface 4 .

[0053] Advantageously but not in a limiting manner, the lower compaction surface 20 is operated, advantageously by the aforesaid motori zed roller 18 , so as to slide in the same advance direction A and substantially at the same speed as the transport surface 4 , so as to avoid relative scraping .

[0054] According to some advantageous but non-limiting embodiments , such as for example the ones shown in figures 2 , 5 , 7 and 8 , the lower compaction surface 20 coincides with the transport surface 4 ; more in detail , advantageously but not in a limiting manner, the lower compaction surface 20 defines at least part of the transport surface 4 .

[0055] In this case (namely, when the compaction device 1 comprises the further lower belt compaction element 17 ) , advantageously but not limitingly, in the predetermined compaction zone 11 , the upper pressing roller 14 is configured to press the upper compaction surface 8 towards the lower compaction surface 20 , which is held in position by the lower pressing roller 14 .

[0056] Advantageously but not limitingly, the upper pressing belt 7 comprises ( in particular, is made of ) a metal material , for example steel . Alternatively or in combination, advantageously but not in a limiting manner, the upper pressing belt 7 comprises ( in particular, is made of ) a plastic material .

[0057] Similarly to the upper pressing belt 7 , when available , the lower pressing belt 19 also is , advantageously but not limitingly, made of a metal material , for example steel , or of a plastic material or of a combination thereof , for example a composite material comprising a metal material and a plastic material .

[0058] In use , the layer 2 of powder material is caused to advance , advantageously but not limitingly, in a continuous manner, by the transport surface 4 through the predetermined compaction zone 11 , where the layer 2 of powder material is compacted, thanks to the action of the pressing rollers 13 and 14 , as it advances along the advance direction A.

[0059] Advantageously but not limitingly, in use ( in particular, under operating conditions , i . e . when compacting) said rollers 13 and 14 are mutually movable to change the extension ( in particular, the thickness ) of the gap defined, at the predetermined compaction zone 11 , between the upper compaction surface 8 and the transport surface 4 or, when available , the lower compaction surface 20 , so as to compact the layer 2 of powder material that , in use , advances between them . More in particular, the pressing rollers 13 and 14 are mutually movable to bring the transport surface 4 (more in particular, the lower compaction surface 20 ) and the upper compaction surface 8 closer to one another .

[0060] According to some advantageous buy non-limiting embodiments like the one shown in the accompanying figures , the lower pressing roller 13 is fixed mounted on the frame 3 , whereas the upper pressing roller 14 is connected to at least one j ack or to another moving system, which can change the height thereof , namely the distance from the lower pressing roller 13 , for example depending on the thickness of the layer 2 of powder material to be compacted and / or on the compaction pressure to be applied to said layer 2 in order to obtain a continuous strip 10 of ceramic powder material of a given thickness .

[0061] With special reference to figures 10 and 12 , advantageously but not limitingly, the compaction device 1 comprises at least one pressing cylinder 31 , instead of the abovementioned j ack; in particular, in the il lustrated embodiments, a pair of pressing cylinders 31, advantageously but not restrictively hydraulic, which act on the upper pressing roller 14 to modify its height, i.e. the distance with respect to the lower pressing roller 13 in operating conditions, i.e. when of compaction. More advantageously but not limitatively, said pressing cylinders 31 transmit to the upper pressing roller 14 a force directed downwards (in particular, towards the lower pressing roller 13) so as to press the upper compaction surface 8 towards the lower compaction surface 20 (hold in position by the fixed lower pressing roller 14) and apply the desired compacting pressure on the layer 2 of powder material which, in use, advances between them and, at the same time, at least partially counteract the expansion action exerted in use by the aforementioned layer 2 of powder material which passes through the aforementioned gap.

[0062] More advantageously but not limitatively, this force transmitted from the pressing cylinders 31 to the upper pressing roller 14 varies between approximately 0.5 and approximately 7 MN.

[0063] According to some advantageous but non-limiting embodiments like, for example, the one shown in the accompanying figures (see, in particular, figures from 9 to 12) , the compaction device 1 comprises an adjustment assembly 32 configured to adjust the distance between the aforementioned lower and upper pressing rollers 13, 14 along a vertical direction, in other words, perpendicularly to the transport surface 4, in resting condition (i.e. before the reciprocal movement of the pressing rollers 13, 14 is actuated to carry out the aforementioned compaction) , as the thickness of the continuous strip 10 of compacted ceramic powder material intended to be obtained and / or the level of compaction intended to be obtained varies. In other words, the adjustment assembly 32 allows the thickness of the gap to be adjusted as the thickness of the continuous strip 10 of compacted ceramic powder material that is intended to be obtained and / or the level of compaction that is intended to be obtained varies

[0064] With special reference to figures 9, 10, 11 and 12, advantageously but not limitingly, the adjustment assembly 32 comprises at least one spacer 33 (in particular, in the accompanying figures, two spacers 33 on each side, each) operatively interposed between the upper pressing roller 14 and the lower pressing roller 13 and operable along a vertical direction (in particular, substantially perpendicular to the transport surface 4) between a maximum extension configuration, wherein the upper pressing roller 14 and the lower pressing roller 13, in a non-operational condition (i.e. before the reciprocal movement of the pressing rollers 13, 14 is actuated to perform the above- mentioned compaction) , are at a first distance from each other along the vertical direction and the gap has a first thickness (see figures 4, 5, 5A, 11 and 12) and a minimum extension configuration, wherein the upper pressing roller 14 and the lower pressing roller 13, in the above-mentioned non-operational conditions, are at a second distance from each other, which is less than the first distance, and the gap has a second thickness, which is less than the first thickness (see Figures 1, 2, 2A, 9 and 10) .

[0065] More advantageously but not limitatively, the adj ustment assembly 32 further comprises an actuator (not visible in the accompanying figures ) , e . g . an electric motor, connected to ( in particular, to each) spacer 33 to move it from the aforementioned minimum extension configuration to the aforementioned maximum extension configuration, and vice versa .

[0066] According to some advantageous , but not limiting, embodiments , the adj ustment assembly 32 comprises at least one positioner 34 ( in the accompanying figures , two positioners 34 on each side - one for each spacer 33 , each) integral with the lower press ing roller 13 ; more advantageously, by means of the interposition of a lower plate 35 which is carried by the frame 3 ( in particular, which is part of the frame 3 ) and is fixed to the lower pressing roller 13 , and the ( in particular, each) spacer 33 is an oleodynamic cylinder coupled to the ( in particular, to a respective ) pos itioner 34 to be able to move with respect to the positioner 34 along the aforementioned vertical direction so as to be able to switch from the maximum extension configuration to the minimum extension configuration and vice versa .

[0067] Even more advantageously but not limitatively, the compaction device 1 (more advantageously, the frame 3 ) also comprises an upper plate 36 , which is integral with the upper pressing roller 14 , and the adj usting assembly 32 ( in particular, at least the spacer 33 - each of the spacers 33- and the positioner 34- in particular, each of any positioners 34 ) is operatively interposed between said upper plate 36 and the lower plate 35 to adj ust the aforementioned distance between the lower and upper pressing rollers 12 , 14 . According to some advantageous but not limiting embodiments , when the adj usting assembly 32 comprises several spacers 33 , each of said spacers 33 is operable independently of the others ; in other words , an actuator is provided for each spacer 33 to operate it between the aforementioned maximum and minimum extension configurations and vice versa independently of the others . This increases the flexibility o f the compacting device 1 by allowing, for example , to cope with ( in particular, to at least partially compensate for ) any irregularities in the loading of the layer 2 of powdered material .

[0068] According to some advantageous but non-limiting embodiments like , for example , the one shown in the accompanying figures , the upper pressing roller 14 is interposed between the motori zed roller 6a and the idle pulley 6b in contact with the upper pressing belt 7 ( in particular, with an inner face of the upper pressing belt 7 ) . More advantageously, though not in a limiting manner, in this case , the upper pressing roller 14 coincides with one of the rollers of the plurality of rollers 6a, 6b around which the upper pressing belt 7 is wound .

[0069] Similarly, advantageously but not limitingly, the lower compaction roller 13 is in direct contact with the transport surface 4 .

[0070] When the aforesaid further lower belt compaction element 17 is provided, advantageously but not limitingly, the lower pressing roller 13 is in direct contact with the lower pressing belt 19 . More advantageously but not limitingly, the lower pressing rol ler 13 coincides with ( in particular, is ) one of the rollers 18 of the plurality of rollers 18 of the lower belt compaction element 17 .

[0071] Furthermore , the compaction device 1 advantageously comprises an upper countering element 21 (namely, a guide element 21 ) , which is arranged upstream of the upper pressing roller 14 along the advance direction A and is conf igured to act upon the inner side of the lower branch of the upper pressing belt 7 in the area of the aforesaid invitation zone 12 so as to limit , in use , the deformation to which the upper pressing belt 7 is subj ected when the layer 2 of power material in fed in the area of the invitation zone ( see figures 2 , 2A, 5 , 5A, 6 , 8 , 8A, 8B, and 8C ) .

[0072] Advantageously but not limitatively , said countering element 21 is arranged at a distance from the upper pressing roller 14 along the advance direction A of about 1500mm at most .

[0073] According to some advantageous but non-limiting embodiments , for example like the one shown in figures 2 , 2A, 5 , 5A, 6 and 8 , said countering element 21 comprises ( in particular, consists of ) an auxiliary roller having a hori zontal rotation axis perpendicular to the advance direction A. Advantageously but not limitatively, said auxiliary roller has a diameter ranging from about 50mm to about 300 mm; more advantageously, equal to about 150mm .

[0074] Alternatively or in combination, according to other advantageous but non-limiting embodiments , for example like the one shown in figure 8C, the countering element 21 comprises ( in particular, consists of ) a series of auxiliary rollers , in the example shown herein four auxiliary rollers , each having a hori zontal rotation axis perpendicular to the advance direction and a diameter ranging from about 50mm to about 300 mm; more advantageously, a diameter of about 100mm . Advantageously, the use of one or more rollers as countering elements 21 ( as shown in the embodiment represented in figures 1 to 8 and 8C ) permits to act upon the upper pressing belt 7 through rolling, thus eliminating or anyway minimi zing the possible scarping in the point of contact between the countering element 21 and the upper pressing belt 7 , with clear advantages in terms of wear of the belt 7 and, hence , li fe of the upper pressing belt 7 .

[0075] According to other advantageous though non-limiting embodiments , for example like the ones shown in figures 8A and 8B, said countering element 21 comprises ( in particular, consists of ) a properly shaped pad, for example a rubber pad, which extends on a plane substantially parallel to the transport surface 4 , crosswise to the transport surface 4 and perpendicularly to the advance direction A, and is configured to act upon the inner side of the pressing belt 7 in order to limit the deformation thereof as much as possible . With special reference to figure 8A, according to some advantageous but non-limiting embodiments , said pad has a rounded contact surface to limit the scraping when acting upon the upper pressing belt 7 . According to other nonlimiting variants , for example like the one shown in figure 8B, said pad has a substantially flat contact surface .

[0076] According to yet other advantageous but non-limiting embodiments which are not shown herein, said countering element 21 comprises ( in particular, consists of ) a countering plate , which extends above the transport surface 4 perpendicularly to the advance direction A, or a properly shaped section bar, for example made of rubber, or a guide , which extends on a plane substantially parallel to the transport surface 4 , crosswise to the transport surface 4 and perpendicularly to the advance direction A, and is configured to act upon the inner side of the pressing belt 7 in order to limit the deformation thereof as much as possible .

[0077] More advantageously, the compaction device 1 comprises a moving system 22 configured to move the countering element 21 along a translation direction B having at least one component perpendicular to the transport surface 4 , so as ( at least partly) adj ust the inclination of the upper compaction surface 8 relative to the advance direction A at least in said invitation zone 12 ( see , for example , figures 2 , 2A, 5 , 5A, 6 , 8 , 8A, 8B, and 8C ) .

[0078] More advantageously but not limitatively, the moving system 22 can be operated to adj ust the position ( in particular, at least the height ) of the countering / guide element 21 , depending on the defined thickness of the gap, so as to make sure that the countering / guide element 21 acts upon the inner side of the upper pressing belt 7 so as to at least partially counteract the stresses transmitted, in use , to the outside of upper pressing belt 7 by the layer S of power material advancing in the area of the gap .

[0079] According to some advantageous , though non-limiting embodiments , for example like the one shown in figure 6 , the moving system 22 is configured to move the countering element 21 up to a height ( in particular, up to a distance from the transport surface 4 ) such as to cause the upper compaction surface 8 to form, in the invitation zone 12 , a given angle a ranging from about 0 ° to about 15 ° ( in particular, from about 4 ° to about 6 ° ) relative to the advance direction A, namely relative to the transport surface 4 .

[0080] As a matter of fact , experiments have shown that said inclination angle a ( ranging from about 0 ° to about 15 ° ; in particular, from about 4 ° to about 6 ° ) is the ideal angle to ensure a correct feeding of the layer 2 of ceramic powder material in the area of the gap and between the pressing rollers 13 , 14 , avoiding the risk of formation of undesired accumulations of powder material upstream of this gap, which would form due to an excess reduction in case of de formation of the pressing belt 7 and to an increase in the inclination angle ( see , in figure 7 , the angle indicated with ai, which the compaction surface 8 would form with the advance direction A following the deformation of the pressing belt 7 ) , and, at the same time , is the ideal angle to facilitate the expulsion of air ( or, at least , of the largest part of the air ) that could remain trapped inside the layer 2 of ceramic powder be fore it is fed between the rollers 13 , 14 , in case of insuf f icient extension of the invitation zone 12 (namely, in case the compaction surface 8 formed an insuf ficient angle with the advance direction A, in particular smaller than the aforesaid defined angle a) . More advantageously, though not in a limiting manner, said countering element 21 extends perpendicularly to the advance direction A and to said translation direction B so as to act upon the inner side of said lower branch of the pressing belt 7 and said moving system 22 comprises at least one actuator 26 configured to move the countering element 21 along the translation direction B .

[0081] According to some advantageous but non-limiting embodiments , for example like the one shown in figure 6 , the moving system 22 comprises : a fixed support structure 23 connected to the frame 3 ; a trestle 24 , which is connected to the fixed support structure 23 in a sliding manner and carries , at a lower end of its , the countering element 21 ( in particular, the auxiliary roller that defines said countering / guide element 21 in the embodiments of f igures 1 to 8 ) ; or the curved or flat contact surface of the pad that defines said countering / guide element 21 in the embodiments of figures 8A and 8B, respectively; or the series of auxiliary rollers that define said countering / guide element 21 in the embodiment of figure 8C . The moving system 22 further comprises a drive assembly 25 operatively interposed between the fixed support structure 23 and the trestle 24 and configured to move said trestle 24 relative to the fixed support structure 23 along the aforesaid translation direction B . More advantageously, though not in a limiting manner, the moving system 22 is configured to allow a movement (namely, a translation ) along the translation direction B having an extension ranging from about 5mm to about 200mm .

[0082] More advantageously but not in a limiting manner, said drive assembly 25 comprises at least one actuator 26 carried by the fixed support structure 23 ; and at least one articulated j oint 27 operatively interposed between the actuator 26 and the trestle 24 . The presence of said articulated j oint 27 advantageously increases the degrees of freedom of the moving system, so as to ef fectively compensate for all the movements ( it does not matter how small they are ) to which, in use , the fixed support structure 23 is subj ected, for instance because of the vibrations transmitted, in use , by the rest of the components .

[0083] According to some advantageous but non-limiting embodiments , for example like the one shown in the accompanying figures , the fixed support structure 23 comprises ( in particular, consists of ) a beam and the moving system 22 comprises a pair of actuators 26 , one at each side end of the fixed support structure 23 , and a pair of articulated j oints 27 , each interposed between one of the two actuators 26 and the side end of the trestle 24 . This configuration advantageously increases stability and allows for a correct movement of the trestle 24 using small-si zed components .

[0084] Advantageously though not in a limiting manner, the actuator 26 (namely, each one of the actuators 26 ) is of the hydraulic kind . More advantageously but not in a limiting manner, the (namely, each) actuator 26 is in fluid communication with an operating assembly (not shown and of the known kind) comprising a tank, from which it draws oil , and a pump to pressurize said oil , which is the fed, through a suitable delivery duct , to the actuator 26 .

[0085] It should be pointed out that , according to other advantageous , though non-limiting embodiments , the actuator 26 (namely, each one of the actuators 26 ) is of the electric or hydraulic or pneumatic type .

[0086] Advantageously but not in a l imiting manner, the compaction device 1 also comprises an electronic control unit CU ( schematically shown in figure 8 ) configured (namely, programmed) to control the operation of the moving system 22 , for example , in the case shown herein, of the actuators 26 , more advantageously, though not in a limiting manner, depending on the thickness of the layer 2 of powder material comprising ceramic powder and / or on the thickness of the gap so as to make sure that , even i f the operating conf iguration of the compaction device 1 changes , the countering or guide element 21 is tangent to the upper pressing belt 7 and counteracts the deformation thereof .

[0087] According to some advantageous but non-limiting embodiments , for example like the ones shown in the accompanying figures , the aforesaid support structure 23 comprises two parallel side guides 28 , which extend along the aforesaid translation direction B and are arranged at two side ends of the support structure 23 ; and the frame 3 comprises two corresponding tracks 29 configured to receive the guides 28 in a sliding manner so as to guide (namely, constrain) , in use , the movement o f the trestle 24 . In other words , the guides ensure the correct movement of the countering or guide element 21 .

[0088] More advantageously, though not in a limiting manner, the guides 28 and the tracks 29 extend parallel to , namely along, the aforesaid direction B .

[0089] According to some advantageous though non-limiting embodiments , which are not shown herein, when the aforesaid further lower belt compaction element 17 is present , the compaction device 1 also comprises a further lower countering / guide element (not vi sible in the accompanying figures ) , which is arranged upstream of the lower pressing roller 13 and is configured to cooperate with the lower pressing belt 19 in order to support the lower compaction surface so as to hold said further lower compaction surface 20 substantially parallel to said advance direction A. In other words , advantageously but not limitatively, in this case , said further lower countering / guide element is located at a height such that the lower compaction surface 20 , when available , or - more in general - the transport surface 4 remains planar . More advantageously but not limitatively, when available , said further lower countering / guide element comprises ( in particular, consists of ) a further fixed roller (not visible in the accompanying figures ) having a hori zontal rotation axis parallel to the lower pressing roller 13 .

[0090] Furthermore , according to some advantageous , though non-limiting embodiments , the compaction device 1 also comprises an expansion countering plate 30 arranged downstream of the predetermined compaction zone 11 along the advance direction A and configured to maintain the planar character of the transport surface 4 .

[0091] The compaction device 1 of the invention of fers numerous advantages , among which we would like to mention the following ones .

[0092] The compaction device 1 of the invention, thanks to the presence of the moving system 22 o f the countering or guide element 21 allows a precise and accurate adj ustment of the position, in particular in the vertical direction, of said countering or guide element 21 , so as to ensure that it insists on the upper pressing roller 7 , regardless of the operating configuration of the compaction device 1 , namely regardless of the thickness of the products to be processed by said compaction device 1 , thus minimi zing the risk of deformation ( in particular, of bending) of the pressing belt 7 , upon compaction, with a consequent reduction in the risk of formation of irregularities in the feeding of the layer 2 of powder material in the compaction zone 11 , making sure that the angle a formed by the lower compaction surface with the transport surface always remains between 0 ° and 15 ° ; more in particular, between 4 ° and 6 ° .

[0093] Furthermore , the possibility of moving the countering or guide element 21 in the vertical direction also facilitates the operations to be carried out to replace the upper pressing belt 7 . Indeed, during the operations to be carried out to remove the pressing belt 7 to be replaced, the possibility of li fting the countering or guide element allows the belt to be loosened in a quicker and more ef fective manner .

Claims

C L A I M S1. A compaction device (1) for compacting a layer (2) of powder material comprising ceramic powder; the compaction device (1) comprises: a transport surface (4) configured to receive and advance said layer (2) of powder material comprising ceramic powder in an advance direction (A) ; a belt compaction element (5) , which, in turn, comprises a plurality of rollers (6a, 6b) , each having a respective rotation axis perpendicular to said advance direction (A) , and a pressing belt (7) wound around said plurality of rollers (6a, 6b) so as to define, with a lower branch thereof, a compaction surface (8) , which substantially faces said transport surface (4) and is movable along said advance direction (A) ; a first pressing roller (13) , which has a rotation axis perpendicular to said advance direction (A) , is arranged below said transport surface (4) and cooperates with said transport surface (4) ; a second pressing roller (14) , which is parallel to and placed above to said first pressing roller (13) and cooperates with the compaction surface (8) in order to press said compaction surface (8) towards said transport surface (4) , at a predetermined compaction zone (11) , so as to compact said layer (2) of powder material; and a countering element (21) , which is arranged upstream of said second pressing roller (14) , along said advance direction (A) , and is configured to act upon the inner side of said lower branch of said pressing belt (7) at an invitation (feeding) zone (12) , which extends upstream ofsaid predetermined compaction zone (11) along said advance direction (A) ; the compaction device (1) is characterized in that it comprises a moving system (22) configured to move said countering element (21) along a translation direction (B) having at least one component perpendicular to said transport surface (4) , so as to adjust the inclination of the compaction surface (8) relative to said advance direction (A) at least at invitation (feeding) zone (12) .

2. The compaction device (1) according to claim 1, wherein : said second pressing roller (14) is configured to press said compaction surface (8) towards said transport surface (4) so that, at said predetermined compaction zone (11) , a gap having a defined thickness is defined between them; said moving system (22) can be operated as a function of said defined thickness of said gap so that said countering element (21) acts upon the inner side of said pressing belt (7) in order to at least partially counteract the stresses transmitted, in use, to said pressing belt (7) by said layer (2) of powder material which advances at said gap.

3. The compaction device (1) according to claim 1 or 2, wherein said moving system (22) is configured to move said countering element (21) up to a height (in particular, up to a distance from the transport surface (4) ) such as to cause said compaction surface (8) to form, in said invitation zone (12) , an angle (a) ranging from about 0° to about 15° (in particular, from about 4° to about 6°) relative to said advance direction (A) .

4. The compaction device (1) according to any one ofthe preceding claims, wherein: said countering element (21) extends perpendicularly to said advance direction (A) and to said translation direction (B) so as to act upon said inner side of said lower branch of said pressing belt (7) and said moving system (22) comprises at least one actuator configured to move said countering element (21) along said translation direction (B) .

5. The compaction device (1) according to any one of the preceding claims, comprising a frame (3) to carry said transport surface (4) and said belt compaction device (5) ; said moving system (22) comprising: a support structure (23) connected to said frame (3) , a trestle (24) , which is connected to said support structure (23) in a sliding manner and carries, at a lower end of its, said countering element (21) ; and a drive assembly (25) operatively interposed between said support structure (23) and said trestle (24) and configured to move said trestle (24) relative to said support structure (23) along said translation direction (B) .

6. The compaction device (1) according to claim 5, wherein said drive assembly (25) comprises at least one actuator (26) carried by said support structure (23) ; and at least one articulated joint (27) operatively interposed between said actuator (26) and said trestle (24) .

7. The compaction device (1) according to claim 5 or 6, wherein: said support structure (23) comprises two parallel side guides (28) , which extend along said translation direction (B) and are arranged on two opposite sides of said support structure (23) ; and said frame (3) comprises two tracks (29) configured to receive said guides (28) in asliding manner so as to guide, in use, the movement of said trestle (24 ) .

8. The compaction device (1) according to any one of the preceding claims, wherein said countering element (21) comprises an auxiliary roller having a rotation axis perpendicular to said advance direction (A) .

9. The compaction device (1) according to any one of the preceding claims, comprising a further belt compaction element (17) , which, in turn, comprises a further plurality of rollers (18) , each having a respective rotation axis perpendicular to said advance direction (A) , and a further pressing belt (19) wound around said further plurality of rollers (18) so as to define, with an upper branch thereof, a further compaction surface (20) , which substantially faces and is in direct contact with said transport surface (4) and is movable along said advance direction (A) ; in particular, said further compaction surface (20) coincides with said transport surface (4) .

10. The compaction device (1) according to claim 9, comprising a further countering element, which is arranged upstream of said first pressing roller (13) and cooperates with said further pressing belt (19) to support said further compaction surface (20) so as to hold said further compaction surface (20) substantially parallel to said advance direction (A) ; said further countering element comprising a further auxiliary roller having a rotation axis perpendicular to said advance direction (A) and substantially parallel to said rotation axis of said first pressing roller (13) .

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