A device for forming ceramic products, including slabs, tiles and the like, by powder pressing

Abstract

 The device comprises: a lower element (2) bearing a lower rest plane (3) for supporting materials to be pressed, the lower rest plane (3) also forming a lower surface of closure of the device; the lower element (2) resting slidably on a lower pressing organ; an upper element (4) which is elastically deformable and provided with at least one active surface (5), which active surface (5) is predisposed to face the lower rest plane (3); a forming frame (6) which projects below a downwards-facing surface of the upper pressing organ and which is predisposed above the upper element (4) and delimits a perimeter of a pressing zone. The forming frame (6) also generates, following a pressing operation, an edge (22) of a final pressed piece (21) which exhibits a greater compaction and therefore a greater density than other zones of the final pressed piece (21).

Description

[0001] The prior art in the field of tile forming is based on the use of dies, inserted in presses, which are, generally speaking, constituted by a cell, internally of which the powders are deposited, and by at least one punch or top die, which has the task of pressing the previously-deposited powders in the cell.

[0002] The prior art also teaches the use of dies in which the cell is not afforded in the bottom die, which is instead constituted by a plane on which a layer of powders is deposited, which is then pressed by the punch or top die. The delimitation and lateral containing of the material to be pressed to form the tile or slab is formed by a frame associated to the punch or top die, the frame being mobile with respect to the punch so as to project inferiorly therefrom in order to come into contact and remain in contact, during the pressing operation, with the plane on which the layer of powders has been deposited.

[0003] This latter solution exhibits a certain constructional complexity, due to the need to include devices for vertical movement of the frame with respect to the punch; the mobile parts are also subject to wear.

[0004] A further problem exists, and certainly not an easy one, as it relates to the need to include a device which cleans the punch or top die between one pressing operation and another.

[0005] The prior art includes publication EP 1136211, which teaches a device for forming ceramic materials, such as slabs, tiles and the like, by pressing powders, in which the material (powders) to be pressed in the form of a layer is predisposed on the rest plane, which is constituted by the upper face of a continual belt, which is supported slidingly on a lower press organ. Pressing is achieved using an upper press organ by interposition of a ring-wound continuous belt, on the external surface of which - the external surface being brought down onto the upper face of the continuous belt - a least one forming frame is arranged, which projects inferiorly and is predisposed in order to create a perimeter delimitation of a closed zone (surface) to be pressed. The forming frame also has the task of generating, following the pressing operation, an edging of the pressed product, characterised by having a greater density than the internal zones.

[0006] The above-described devices all exhibit some important drawbacks and problems.

[0007] One of the most important of these problems is that of performing a good cleaning of the surfaces of the device which come into contact with the pressing powders, and in particular of the external surface of the ring-wound closed belt on which the forming frames are fixed.

[0008] The main aim of the present invention is to obviate the drawbacks inherent in the prior art.

[0009] Advantages of the invention are its constructional and functional simplicity.

[0010] A further advantage of the invention is that it is very precise in positioning the pressed piece, no longer subject to the oscillations of the belt.

[0011] These aims and advantages and more besides are all attained by the invention as it is characterised in the claims that follow.

[0012] Further characteristics and advantages of the present invention will better emerge from the detailed description that follows of a preferred but non-exclusive embodiment of a device for loading powders depositing a layer of powders on a moving conveyor belt, illustrated purely by way of a nonlimiting example in the accompanying figures of the drawings, in which:

figure 1 shows a schematic longitudinal section made according to a vertical plane parallel to the advancement direction of the materials;

figure 2 is a detail of figure 1, in enlarged scale;

figure 3 is a detail of figure 2 in a different operative configuration.

[0013] With reference to the figures of the drawings, 1 denotes in its entirety a device for forming ceramic materials, such as slabs, tiles and the like, by powder pressing. The device 1 is schematically constituted by a press bearing a central opening crossed by a lower element 2 and an upper element 4.

[0014] The lower element 2, bearing a lower rest plane 3 for supporting the material (powders) to be pressed 20, as well as the final pressed piece 21, is constituted by an upper branch of a continuous belt 12.

[0015] The upper element 4 is constituted by the horizontal lower branch of a continuous belt 11, ring-wound and stretched between externally-positioned parallel-axis drums 16, which belt 11 is driven synchronically with the belt 12 constituting the lower element 2.

[0016] The lower element 2 rests and runs on the upper surface of a lower pressing organ 10, or piston, of the press and is for this reason commanded by the piston 10 to displace upwards in order to exert the pressing action.

[0017] The upper element 4 is elastically deformable and is provided with at least one active surface 5, predisposed to face the lower rest plane 3.

[0018] An upper pressing organ 13 operates above the upper element 4. The upper pressing organ 13 is inferiorly provided with a downwards-facing surface, parallel to and facing the upper surface of the lower pressing organ 10, to which downwards-facing surface a containing edge, or forming frame 6 is constrained.

[0019] The forming frame 6 projects inferiorly with respect to the downwards-facing surface of the upper pressing organ 13, and has the aim of delimiting a perimeter of a predefined pressing zone.

[0020] In particular, the forming frame 6 generates, following a pressing operation, an edge 22 on the final pressed piece 21, characterised by a greater compacting, or density, with respect to the other parts of the piece 21.

[0021] The upper element 4 is constituted by the lower branch of a ring-wound continuous belt 11 stretched between externally-positioned parallel-axis drums 16.

[0022] The belt 11 is elastically deformable, and the material constituting the forming frame 6 is also considerably elastically deformable and can have, according to needs, different straight transversal sections. For example, in the illustrated embodiment, the forming frame 6 has a straight triangular transversal section, while in another embodiment, not represented in the accompanying figures of the drawings, it might advantageously have a straight rectangular section.

[0023] The difference in the shapes of the transversal sections of the forming frame 6 enables the edges 22 of the final pressed piece to be characterised by different shapes, to which a different distribution of compactness can correspond.

[0024] The forming frame 6 is preferably "covered" by a layer 7 of elastically-deformable material having a uniform thickness, which is fixed, with a predetermined tension, to the lower surface 14 of the upper pressing organ 13. In particular, the forming frame 6 is glued to the layer 7.

[0025] By effect of the elastic deformability of the layer 7 and the element 4, the pressing action, thanks to the presence of the forming frame 6, produces a greater compacting of the surface covered by the forming frame 6, thus realising a delimiting of the internal zone by generation of an edge 22 of the final pressed piece 21.

[0026] During the pressing operation, the lower pressing organ, or piston 10, rises, lifting the part of the lower element 2 on which the layer of powders was previously deposited, compressing the layer against the active surface of the upper element 4.

[0027] The internal area which is compressed is peripherally delimited by the action of the forming frame 6 which is exerted through the medium of the layer 7 which is elastically deformable.

[0028] Thus a greater pressure is generated in the perimeter area, with respect to the centre, creating an edge of the slab or tile which more compacted - this is in fact the edge 22 of the pressed piece 21.

[0029] The presence of this area, which will subsequently be removed by a cut, functions as a containing border, which during the pressing operation has the important function of enabling a regular and uniform formation of the internal zone and, especially, preventing of the formation of cracks or fissures or irregularities in the body of the slabs.

[0030] At the end of the pressing operation, the element 4, the layer 7 and the forming frame 6 return to the undeformed state and configurations, as shown in figure 2.

[0031] In particular, the active surface 5 of the element 4 returns to its original flat configuration, and is therefore easily cleanable once the interested portion thereof is out of the press area, following the advancement of the continuous belt 12.

[0032] An advantage of the invention is that the slab and/or tile forming operation is rendered very simple and rapid, especially where pieces of large size and small thickness are concerned.

Claims

1. A device for forming ceramic materials, including slabs, tiles and the like, by powder pressing, comprising:

a lower element (2) bearing a lower rest plane (3) for supporting materials to be pressed, the lower rest plane (3) also forming a lower surface of closure of the device; the lower element (2) resting slidably on a lower pressing organ (10);

means for superiorly and perimetrally delimiting a pressing zone, which means are located superiorly of the lower rest plane (3) and inferiorly of an upper pressing organ;

characterised in that the means for superiorly and perimetrally delimiting a pressing zone comprise: an upper element (4) which is elastically deformable and provided with at least one active surface (5), which active surface (5) is predisposed to face the lower rest plane (3);
a forming frame (6) which projects below a downwards-facing surface of the upper pressing organ and which is predisposed above the upper element (4) and delimits a perimeter of a pressing zone; the forming frame (6) also generating, following a pressing operation, an edge (22) of a final pressed piece (21) which is characterised by exhibiting a greater compaction and therefore a greater density than other zones of the final pressed piece (21).

2. The device of claim 1, characterised in that the upper element (4) having at least one active surface (5) is constituted by a lower branch (15) of a ring-wound continuous belt (11) which is stretched between externally-positioned drums (16) having parallel axes.

3. The device of claim 1, characterised in that at least the forming frame (6) is constituted by a material having a high degree of elastic deformability.

4. The device of claim 1, characterised in that the forming frame (6) is covered by a layer of elastically-deformable material which is of a uniform thickness, which layer is fixed to the upper pressing organ with a predetermined tension.

5. The device of claim 1, characterised in that the lower element (2) bearing the lower rest plane (3) for supporting the materials to be pressed and the final pressed piece (21) is constituted by an upper branch of a continuous belt (12) which is moved synchronically with the lower branch (15) of the other continuous belt (11).

Drawing