Loading system for the moulds of ceramic presses for forming pressure-glazed tiles, and relative implementation means

Abstract: A system for loading a multi-component soft mass into the moulds (2) of ceramic tile-forming presses, said moulds comprising at least one forming cavity (3) for tile compaction, characterised by temporarily placing on a movable horizontal belt (8) at least one layer of powder material, and, by means of said belt, transferring into said at least one cavity said at least one layer of powder material, without causing it to undergo horizontal displacement.

Description: In the most recent tile manufacturing technology, the loose material fed to the forming mould is already coloured, to enable pressed tiles to be prepared having throughout their bulk a distribution of one or more colours which on appearing at the surface form the final tile decoration. The materials obtained in this manner are commonly known as porcellainized ceramic stone. The known technology in the production of porcellainized ceramic stone tiles does not however enable tiles to be manufactured having a determined geometrical decoration, such as that obtained for example with known silk-screen methods, nor does it enable tiles with different bulk colorations and decorations to be produced in succession on the same line. The object of the present invention is to provide a method for feeding the loose material into the cavities in the tile forming moulds by which the same line is able to produce different or differently combined bulk colorations, and also provide decorations similar to those obtained by a silk-screen process. Said object is attained according to the invention by the features of claim 1. JP-A-05-104 518 discloses a method and an apparatus in which a layer of powder is temporarily placed on a movable horizontal shiftable surfaces (a belt) suitable for transferring said layer into the cavuty of a mould without causing it to undergo horizontal displacement. This document does not give any teaching in order to provide at least two translationally shiftable surfaces, each carrying at least one layer of powders. EP 0 300 532 discloses an apparatus for feeding at least two layers of powder into the cavity of a mould, at least one of said layers, (the upper pattern layer) being fed to the mould cavity by a shiftable surface (a belt), without causing the powder to undergo horizontal displacement. The apparatus and method of EP 0 300 532 present the drawback that the upper part of the mould must be distant from the cavity in order to leave free enough space for the passage of both the slide intended to feed the ground layer and the belt intended to feed the pattern layer of the tile. The invention also comprises a plant for implementing the aforesaid forming system. According to the invention, the plant comprises a certain number of vessels each intended to contain a single-colour material in the form of powder. If the tiles are to have a geometrical surface decoration, at least some of said vessels, in particular those intended to contain the decoration colours, are provided with means for distributing the material on a suitable support surface, such as a translationally shiftable belt, to be called the collection belt, via means arranged to intercept the falling material flow, to shape it in accordance with the desired pattern. These latter means can conveniently be frames having a cloth surface with rarefied or permeable regions through which the material passes, spaced apart by dense or impermeable regions, which prevent the material from passing. Said frames are provided in a number equal to the number of mould cavities to be fed, and are distributed in the same manner as these latter. A single frame could also be provided having apertures occupied by screens spaced apart by solid regions, and on which a powder distribution means moves translationally. If the decoration is single-coloured, said frames can be replaced by masking covers distributed on an endless continuous flexible support along a path a portion of which overlies the collection belt and is parallel thereto. By causing the flexible support to move translationally, lines of different masking covers can be brought into the working position, which makes it possible to very rapidly change the type of decoration on the manufactured product. As stated, via each individual masking cover there is deposited by gravity on the collection belt a first layer of coloured material having in plan view the desired configuration, this latter being inscribable within the perimetral contour of the respective forming cavity of the ceramic mould. Said first layer preferably has a thickness of between 0.1 and 5.0 mm. At each deposition of the decoration, the collection belt advances through a step at least equal to that dimension of the mould forming cavity in the direction of advancement of said belt. According to the invention, on said first layer there is then gravity-deposited a second layer of powder material originating from a second vessel, said second layer, intended to form the background to the first layer, having in plan view a shape substantially identical to the perimetral contour of the forming cavity. Said second layer preferably has a thickness of between 0.3 and 20 mm. The first layer can be formed for example by a distributor arranged to slide parallel to the underlying line of masking covers, and the second layer can be formed by a normal web distributor fed by a hopper. Again, the second layer can either form merely the background to the decoration or also form the tile body. Preferably, the second layer is temporarily formed on an intermediate support surface, such as an intermediate belt positioned above the collection belt on which the first layer is deposited. Suitable sensor means, such as photoelectric cells, sense the passage of the first layer made to advance by the collection belt, and feed a signal to the drive means of the overlying intermediate belt, so that this latter is made to transverse at the same speed as the underlying belt, said second layer being deposited on the first. At this point the collection belt, which is conveniently supported by a loading device positioned in front of the ceramic mould, can be made to advance towards this latter until the front generating line of its upper portion comes into vertical alignment with the edge of that forming cavity situated on the opposite side to that where said loading device is located. When in said position, the collection belt is driven forwards until the front region of the two superposed layers of powder material reaches the front end of the belt, after which the belt is pulled rearwards by the loading device at a shifting speed equal to the belt operating speed. By the combination of said two simultaneous movements the powder layers are deposited by gravity on the base of the forming cavity substantially with the same distribution and/or arrangement which they had before being transferred. On termination of this transfer the loading device retracts completely to begin a new loading cycle. In particular, if the second layer is intended to form not only the background to the decoration but also the bulk of the tile, the tile is compacted immediately after said transfer. If however the bulk of the tile is to be formed by less valuable material, this is fed as a third layer to the collection belt to cover the first two layers. Said third layer has a thickness preferably of between 5 and 20 mm. In a particular embodiment of the plant of the invention a first and a second intermediate belt coplanar with each other lie above the collection belt. The first intermediate belt is overlaid by a hopper containing the tile background material intended to form most of the unexposed bulk of the tile. The second intermediate belt is overlaid by a series of loading hoppers each containing a single-colour material. All the hoppers of the series are loaded by a common upper feed belt which can be positioned with its end gradually overlying each of the hoppers, and receives powders of different quality from overlying silos. Said powders are stratified on the feed belt and transferred into the underlying hoppers either as such or partially mixed. The operation of the system according to the invention and the characteristics and constructional merits of the relative means of implementation will be more apparent hereinafter by reference to the figures of the accompanying drawings, which illustrate some preferred embodiments thereof by way of example only. Figure 1 is a schematic side view of an embodiment which does not form part of the invention. Figure 2 is a view in the direction II of Figure 1. Figure 3 is a section on the line III-III of Figure 1. Figure 4 is a section on the line IV-IV of Figure 1. Figure 5 is a section on the line V-V of Figure 1. Figure 6 is a schematic side view of a first embodiment of the invention. Figure 7 is a schematic side view of a second embodiment of the invention. Said figures show a usual ceramic press 1, on which in the illustrated example there is mounted a mould 2 with three cavities. On the feed side of said press there is positioned a loading device 4 which can be moved translationally between an advanced position and a withdrawn position by the action of a geared electric motor unit 5. The geared motor unit 5 rotates a connecting rod 6 connected to the frame 7 of the collection belt 8 of the loading device 4. The collection belt 8 extends between a motorized rear roller 9 and an idle front roller 10, with which there is associated a usual pusher with scraper 333 for discharging the formed tiles and removing excess powder mixture. The motorized rear roller 9 is driven by a geared electric motor unit 11 via a toothed belt transmission 12 and a free-wheel pulley 14. The free wheel 14 transmits motion only in the direction of advancement of the belt 8 towards the press. On the shaft of the roller 9, on the other side to the free wheel 14, there is a second free wheel 15 which engages an overlying fixed rack 16. By virtue of the free wheel 15, during the advancement of the frame 7 towards the press, the belt remains stationary, whereas during the withdrawal of the frame 7 in the opposite direction the belt 8 advances through a distance equal to the distance through which the frame 7 has withdrawn. This is due to the fact that the direction of engagement of the free wheel 15 is the opposite of the direction of engagement of the free wheel 14. Starting from that end facing the press, the collection belt 8 is overlaid by a first feed belt 17 above which there is a hopper 18 and which is operated when required by a geared electric motor unit, not shown, and a second feed belt 19, coplanar with the first and above which there are four transverse hoppers A1, B1, C1, D1. The hopper 18 and the hoppers A1...D1, which are provided with lower closure gates, are as wide as the front of the press and as the underlying belts 17, 19 and 8, are overlaid by a traversing distributor 181, 20, 21, 22, 23 respectively, which receives a flexible feed tube 182, 200, 201, 202, 203 respectively. The flexible tube 182 is connected to an overlying silo, not shown. The flexible tubes 200, 201, 202 and 203 are connected to overlying collection vessels A, B, C and D respectively, containing four different types of mixture of powder material. The hoppers A1...D1 are movable vertically from a position adjacent to the belt 19, to a raised position. Upstream of the belt 19 there is a further belt 24, namely the screen-carrying belt, which passes about four rollers 240 and has a flat portion lying above and adjacent to the belt 8. The belt 24 is as wide as the underlying belt 8 and carries a succession of decoration screens 241 arranged in lines of three (see Figure 4). Above the lower flat portion of the belt 24 there is a hopper 33 provided with a lower closure gate, not shown, and served by a feeder 25 driven with reciprocating movement and connected to an overlying material container, not shown, by the flexible tube 34. At least one of the rollers 240 is motorized in order to drive the belt 24 so as to bring the desired line of decoration screens 241 into the horizontal flat position. The collection vessels A, B, C and D are overlaid by a distributor belt 26 passing about two rollers 260 mounted on a frame 27 which can be moved translationally in a horizontal direction to position the end of the belt 26 above one or another of said collection vessels. Above the distributor belt 26 there is a loading belt 28 which passes about two rollers 280 fixed to the machine base and is positioned below four large vessels or silos 29, 30, 31 and 32, each of which is provided with a lower closure gate, not shown, and contains single-colour powder of various qualities. On the belt 28 there is provided a blade mixer 36 or equivalent, driven by a geared motor unit 35, which is operated when desired. The drive means for the belts 26 and 28 and for the frame 27 will not be described as they are of usual type. The operation of all the motorization and drive means of the plant are controlled by a microprocessor programmed to provide the following operation. From the vessels 29, 30, 31, 32 one or more of their contained materials are made to fall onto the belt 28 to obtain the desired mixture, which is then discharged onto the underlying belt 26 after being mixed by 36. By horizontal translational shifting, the belt 26 causes its end to lie above that collection vessel A, B, C or D to receive the prepared material mixture, which is then discharged into it. Each vessel feeds the underlying hopper A1, B1, C1, D1 via the respective flexible tube 200, 201, 202, 203 and the respective reciprocating feeder 20, 21, 22, 23. Control means of usual type ensure that a sufficient quantity of material is present in each of said vessels and said hoppers, each of which hence contains a material of different quality. The hopper 18 containing the base material and the hopper 33 containing the decoration material are kept fed by analogous means, not shown. In the more complicated case in which a set of three tiles are to be formed having a certain decoration, a coloured background for said decoration and a body formed from a mass of less valuable base material, starting from the situation shown in Figure 1 the plant is caused to operate as follows. By opening the gate of the hopper 33 a certain powder pattern defined by the screens 241 is made to fall onto the belt 8. The powder layer is made to advance by the belt 8 until, on passing below the end of the belt 19 at the same speed thereas, it receives a convenient layer of background material discharged in the illustrated example by the hopper C1, which at the appropriate moment is closed and raised into its rest position. Lastly, by again advancing the belt 8 a third layer of base material is discharged from the hopper 18 onto said two layers. At this point three layers of powder corresponding exactly to the tile being formed are present on the belt 8, which travels until said three layers are brought into proximity with its end. By subsequent advancement of the frame 7 carrying the belt 8, the end of this latter is brought into the position shown by dashed lines in Figure 1. At this point the frame 7 begins to withdraw, the belt 8 begins to shift translationally under the action of the rack 16 and the free-wheel pinion 15, so that the three layers are discharged into the underlying mould cavity 3 without mixing. When the withdrawal of the frame 7 and relative belt 8 is complete, the cycle can be repeated either as such or in a simplified form. Finally, it should be noted that the thickness of said three layers lies within the initially stated ranges. In a first method for implementing the invention, the loading device 4 shown in Figure 1 is formed as shown in Figure 6, in which it consists of a single frame 7 which supports two aligned collection belts 81 and 82 and is connected to the geared motor unit 5 via the connecting rod 6. The belts 81 and 82 are moved in opposite directions. In this embodiment according to the invention, the hopper 33 causes a certain quantity of powder material to fall through the decoration screens 241, to form a powder pattern on the underlying collection belt 82. The pattern so formed is advanced by the belt 82 as far as the front end of the feed belt 19, which advances at the same speed as the belt 82 to deposit on the powder pattern a uniform layer of background material created by one of the hoppers A1....D1 on said belt 19. Simultaneously the hopper 18 deposits the base material on the feed belt 17, which deposits it on the collection belt which advances at the same speed thereas. At this point all the layers of the tile to be formed are present on the collection belts 81 and 82. The frame 7 is made to move translationally until positioned as shown in the figure with dashed lines and is then made to withdraw while the belt 82 advances because of the provision of the rack 16 and free-wheel pinion 15, to discharge the two layers (pattern and background) in the mould 2. The belt 81 begins to advance, at the withdrawal speed of the frame 70, when its left end is in correspondence with the left end of the mould 2, so as to discharge the base material into the mould. Any excess material is removed by the scraper 333 while the frame 70 returns to its initial position to begin a new material loading and discharge cycle for forming a new tile. In the two aforedescribed embodiments the tile is formed inverted, ie with its exposed side facing downwards, however it could evidently be formed the right way up. For this purpose the plant shown in Figure 7 is used, in which the tile base material depositing device, consisting of the elements 17, 18, 180, 181, 182 shown in Figure 1, is positioned upstream of the device which deposits the material forming the tile background.

Claims: A method for loading a multi-component soft mass into the moulds (2) of ceramic tile-forming presses, said moulds comprising at least one forming cavity (3) for tile compaction, characterised by comprising the following method steps : temporarily placing at least one layer of a powder material on each of two coplanar first and second belts (81, 82) supported by the same frame but operable in the opposite directions; and by means of said belts, transferring in succession into said at least one cavity, and without their mutual mixing, the layers of powder material placed on the belts, without causing them to undergo horizontal displacement. A method as claimed in claim 1, characterised in that the transfer is effected by causing the first belt (82), while stationary, to overlie the mould cavity and then withdrawing the belt while simultaneously operating it to rotate it in the opposite direction to, and at the same speed as that at which it is made to withdraw, then operating the second belt (81), when it itself overlies the mould cavity, at the same speed as its withdrawal but in the opposite direction thereto. A method as claimed in claim 1, characterised in that the powdered material placed on the first belt is coloured powdered material. A method as claimed in claim 3, characterised in that the layer of coloured powdered material is placed on the first belt via means arranged to intercept the falling material flow to shape it in accordance with a desired decorative pattern. A method as claimed in claim 4, characterised in that the intercepting means are masks. A method as claimed in claim 1, characterised in that on said first belt are placed at least two layers of powdered material. A method as claimed in claims 6, characterised in that said at least two layers are of poiwdered material of different colours. A plant for feeding a ceramic tile pressing mould (2) provided with at least one forming cavity (3), comprising a loading device (4) positioned in front of the mould, and arranged to slide between a first position in which it is distanced from this latter and a second position in which it overlies it, and provided with one horizontal surface which itself is movable relative to the device a first powder material dispensing unit (33) arranged to create one layer on said surface; said at least one surface being arranged to slide relative to said device structure such as to place said soft mass in said cavity without subjecting it to horizontal displacement, characterised in that said surface comprises at least two coplanar collection belts (81, 82) driven so as to discharge in the forming cavity the material layers lying on them through the gap which separates them. A plant as claimed in claim 8, characterised in that said loading device (4) comprises a horizontal frame (7) which supports said coplanar collection belts (81, 82), and of which the front edge is provided with a pusher with scraper (333) arranged to remove the pressed tiles (14) from the mould and to clean the press surface. A plant as claimed in the preceding claims 8 and 9, characterised in that each of said collection belts (81, 82) is driven by a motor unit arranged to cause it to shift at a speed which in absolute value is equal to the speed with which the device (4) travels from said second position to said first position or vice versa. A plant as claimed in the preceding claims 8-10, characterised by comprising at least one intermediate belt overlying at least one collection belt, and a second dispensing unit for distributing said powder material onto said intermediate belt. A plant as claimed in the preceding claims 8-11, characterised in that the second dispensing unit comprise at least one of a plurality of hoppers (A1, ... D1) positioned in succession overlying the said at least one intermediate belt. A plant as claimed in the preceding claims 8-12, characterised in that the first dispensing unit comprises at least one hopper (33, 55) fed by a reciprocating device (25, 57) provided with an exit port positioned above a masking cover (241, 530) which intercepts the flow of falling material, to select it in accordance with a predetermined pattern.

Inventors: BELLONI MARIO, ORSINI MASSIMO, BELLONI, MARIO, ORSINI, MASSIMO, Belloni, Mario, c/o Ceramiche Dual S.R.L., Orsini, Massimo, c/o Ceramiche Dual S.R.L.
Applicants: CERAMICHE PROVENZA S R L, IRIS CERAMICA SPA, CERAMICHE PROVENZA S.R.L., IRIS CERAMICA - SOCIETA' PER AZIONI
Application year: 1997
Main classification: B28B13
IPC codes: B28B13