Method and device for loading ceramic press moulds

Abstract: Method for loading powder into ceramic tile forming cavities (2) comprises the following operations: preparing on a surface (21) at least one layer of atomized powder; pressing said at least one layer; covering said at least one pressed layer with a possible further at least one layer of atomized powder; transferring said material layers in succession into a loading hopper (11) of a loading carriage (4); transferring material layers from said hopper (11) to the mould forming cavities (2). Device for loading powder into ceramic tile forming cavities (2) comprises a loading carriage (4) which is provided with at least one loading compartment (7) occupied by a grid (70) and having plan dimensions equal to the dimensions of the mould cavity (2) and which moves between two positions, in one of which the compartment (7) lies above the mould cavity (2) and in the other of which the compartment (7) lies below a loading hopper (11), and comprises a structure (12) driven with reciprocating movement between a position lying above the loading hopper (11) and a position distant therefrom, and on which there are located a motorized belt (21) with a flat portion, at least one service hopper (15) above the upper branch of the belt (21) and having its mouth transverse to the belt (21) and closed by a shutter (28), and a roller (40) pressing elastically on the upper side of the belt (21) and positioned downstream of said at least one service hopper (15) with reference to the direction of advancement of the belt (21), and acting against an underlying counteracting roller (41).

Description: This invention concerns ceramic tile forming processes and the devices for their implementation. It is directed in particular towards so-called porcellainized ceramic stone tiles, in which at least the exposed part consists of a bulk-coloured layer. Said layer is formed from atomized clay, the granules of which are variously coloured by known processes, and which are fed to the mould in the form of soft single-colour masses which, on partial mixing, give rise to multi-colour effects reproducing for example marble veining. Although tiles bulk-coloured throughout their entire thickness are known, the high cost of the materials for creating multi-colour masses has induced manufacturers to use tiles having a large but hidden part of their thickness formed from one low-cost single-colour mass, with only the exposed layer in the form of said single-colour masses partially mixed together. However for high-quality products the bulk-coloured solution is preferred. In bulk-coloured tiles one of the most delicate points in the porcellainized ceramic stone tile manufacturing cycle is the powder feed to the forming mould cavity, on which the distribution of the powder mass within the tile depends. This problem is aggravated by the fact that the various single-colour atomized materials which form said masses often have different characteristics, and hence also a different behaviour during their various handlings. This circumstance is particularly important when preparing products for which an appearance of single-colour or two-colour points possibly of different dimensions distributed regularly throughout the mass is required. To obtain these products the known art involves separately preparing, at a point distant from the press, intensely coloured . single-colour or two-colour granules or flakes which are then independently stored and subsequently transferred to another vessel mixed with atomized powder, to be then fed to the press hopper. The handling involved in the preparation, the mixing and the double storage of said granule or flake products gives rise to i problems which make them difficult to use. In this respect, the large granules or flakes tend to dry and harden, creating problems for their uniform pressing. They also tend to break down into unsuitable dimensions, or to abrade to assume a round shape making their appearance in the final product unpleasant. Document EP 0 822 044 A, which falls under Art 54(3) EPC, discloses a method and device for loading powder into ceramic tile forming cavities comprising a loading carriage and a plurality of loading hoppers. The object of the invention is to prepare and feed said mixtures in such a manner as to avoid said drawbacks. This object is attained by the method and apparatus as defined in independent claims 1 and 5. Prefered embodiments of the invention are disclosed the dependent claims. The specific characteristic of the method and apparatus is that the mixtures, including also the flakes, are prepared in a single operation immediately upstream of and in proximity to the press, so dispensing with all the intermediate handling and storage operations. The invention will be more apparent from the ensuing description of a preferred embodiment of the apparatus for implementing the method given by way of non-limiting example and illustrated on the accompanying drawings. Figure 1 is a partly sectional side view of the invention. Figure 2 is a schematic section through the invention taken on the line II-II. Said figures show a usual press 2 provided with a usual mould 2. The ensuing description relates to a three-impression mould, the invention however also being applicable to moulds with more or less impressions. To the side of the press 1 there is a support platform 3 on which a usual loading carriage 4 slides to feed the material to be compacted into the impression in the mould 2. Said loading carriage 4 moves with reciprocating movement between a material loading position and a material discharge position, it being driven by the geared electric motor 5 via the connecting rod-crank mechanism 6. More specifically, the loading carriage 4 comprises a number of compartments 7 equal to the number of impressions in the mould 2, the compartments being provided with usual internal grids 70. Three compartments are shown in the example. In the part to the front of said loading carriages 7 there is provided a pusher 8 comprising a scraper 9, to the rear of the compartments there being fixed a flat plate 10, to which the connecting rod-crank mechanism 6 is connected. When the loading carriage 4 is in the loading position shown in Figure 1, the loading compartments 7 lie exactly below the lower mouth of the loading hopper 11, whereas when the loading carriage 4 is in the position for discharging the material to be compacted, the compartments 7 lie in correspondence with the impressions in the mould 2, at the same time the lower mouth of the hopper 11 being covered by the flat plate 10. A frame 12 is provided in a position overlying the loading carriage 4, to move continuously to and fro over the upper mouth of the hopper 11, driven by the geared motor 13 via the connecting rod-crank mechanism 14. Said frame 12 upperly supports the service hoppers 15,...,20 and lowerly supports a usual belt conveyor 21 driven by a usual drive, not shown. Each of the hoppers 15, ..., 20 contains a powder of different material characteristics, which is deposited on the conveyor belt 21 to create the superposed material layers thereon. The powder material is fed into each of the hoppers 15,...,20 by a traversing flexible distributor 22,...,27 the lower end of which travels with continuous reciprocating movement along their upper mouths to deposit the material into their interiors in a virtually uniform manner, and which is connected to an overlying vessel by a flexible pipe. Each of the hoppers 15,...,20 is provided with a lower closure gate 28,...,33 operated by a pneumatic unit 34,...,39. Said frame 12 also supports a double-acting cylinder-piston unit 300 fed with compressed air by a compressor, not shown. A frame 301 supporting an idly mounted compacting roller 40 is fixed to the rod of the cylinder-piston unit 300 by known means. Below the belt conveyor 21 in a position corresponding with the compacting roller 40 there is provided an idle counteracting roller 41. The cylinder-piston unit 300 operates in practice as an air spring of adjustable thrust, by which the degree of compaction of the material travelling on the belt between the rollers 40 and 41 can be regulated. The plant operation is controlled by a programmable processor, which coordinates the following operations. The belt 21 is rotated continuously, and collects the respective material from one or more of the hoppers 15 to 18. During belt advancement the material is subjected to the action of the roller 40, which compacts it and crushes the larger-size granules to cause them to assume the desired appearance of irregular flakes. Downstream of the compacting roller the compacted material receives single-colour base material from at least one of the hoppers 19, 20, to complete the tile. During the to-and-fro movement of the frame 12 between the position shown by full lines and the position shown by dashed and dotted lines in Figure 1, the belt continuously discharges superposed ordered layers of material into the interior of the hopper 11. The movement of the belt 21 is continuous, as is the reciprocating movement of the frame 12, so that several layers form in succession one on another within the hopper 11. The reciprocating movement of the frame 12 is controlled by a level probe provided within the hopper 11, such that the quantity of material present in this latter remains virtually constant. Whatever the number of layers present in the hopper 11, the carriage transfers one material layer at a time having the thickness of the loading carriage into the cavity in the mould 2.

Claims: A method for loading powder into ceramic tile forming cavities, comprising the following operations: preparing on a surface at least one layer of atomized powder; pressing said at least one layer; covering said at least one pressed layer with a possible further at least one layer of atomized powder; transferring said material layers in succession into a loading hopper (11) of a loading carriage (4), with reciprocating movement of a structure (12) between a position lying above the loading hopper (11) and a position distant from the loading hopper (11) transferring material layers from said hopper (11) to mould forming cavities (2) by said loading carriage (4) which mover between two positions, in one of which the loading compartment (7) of said loading carriages lies above the mould forming cavities (2) and in the other of which the compartment (7)lies below the loading hopper. A method as claimed in claim 1, characterised in that said layers are transferred into the loading hopper (11) by gravity. A method as claimed in claim 1, characterised in that said layers are transferred into the forming cavities (2) by gravity. A method as claimed in claim 1, characterised in that the layers which form in the loading hopper (11) nave the same plan dimensions as the mould cavitie (2). A device for loading powder into ceramic tile forming cavities comprising a loading carriage (4) which is provided with at least one loading compartment (7) occupied by a grid (70) and having plan dimensions equal to the dimensions of the mould cavity (2) and which moves between two positions, in one of which the compartment (7) lies above the mould cavity (4) and in the other of which the compartment lies below a loading hopper (11), comprising a structure (12) driven with reciprocating movement between a position lying above the loading hopper and a position distant from the loading hopper, and on which there are located a motorized belt with a flat portion, at least one service hopper above (22 to 27) the upper branch of the belt (21) and haying its mouth transverse to the belt (21) and closed by a shutter, (28 to 33) and a roller (40) pressing elastically on the upper side of the belt (21) and positioned downstream of said at least one service hopper (22 to 27) with reference to the direction of advancement of the belt (21) and acting against an underlying counteracting roller (40). A device as claimed in claim 5, characterised in that the loading hopper (11) has the same plan dimensions as the mould cavity (2). A device as claimed in claim 5, characterised in that at least one further service hopper (26, 27) is provided downstream of the pressing roller. A device as claimed in claim 5, characterised in that said movable structure (12) moves between a position in which the end of the belt (21) lies above that end of that loading hopper (11) close to the mould cavity (2), and a position in which the end of the belt (21) lies above that end of the loading hopper (11) distant from the mould cavity. A device as claimed in claim 5, characterised in that the movable structure (12) is driven by a connecting rod and crank (14). A device (40) as claimed in claim .5, characterised in that the pressing roller (40) is connected to the rod of a double-acting pneumatic cylinder-piston unit (300) acting as an air spring.

Inventors: CAVAZZONI GIANPAOLO, CAVAZZONI, GIANPAOLO
Applicants: ARIOSTEA S P A, IRIS CERAMICA SPA, ARIOSTEA S.P.A., IRIS CERAMICA - SOCIETA' PER AZIONI
Application year: 1998
Main classification: B28B13
IPC codes: B28B13