Loading system for the moulds of tile forming presses and relative implementation means

Abstract: A system for loading the forming cavities provided in ceramic press moulds with a soft mass consisting of at least two overlying layers of powder materials having different characteristics comprises filling the mould cavity with a first mixture of powder material, compacting said material in a controlled manner, and depositing on said compacted material a second powder material in such a quantity as to complete the filling of the mould forming cavity before pressing. The plant for implementing the system comprises a loading carriage (4) provided with a usual grid-type compartment, and having a frame structure (40) supporting means arranged to compact by means of a roller (44) in a controlled manner a first layer of soft mass within the mould cavity (3), and a small hopper (42) for feeding a second layer of said soft mass directly into the mould cavity (3) after compacting the first layer.

Description: This invention relates to loading systems for the moulds of ceramic tile forming presses, and devices for implementing such systems. Known forming processes comprise creating a mass of powder material within the compartment of a loading carriage for the press mould. This loading carriage can traverse horizontally, driven by known means, between a loading position and a discharge position for the soft mass to be compacted, consequently it being positioned alternately below a hopper which allows the the material to fall into the compartment, and above the mould cavity into which the previously loaded material is deposited. To remove the formed tile from the mould cavity, the cavity base can move vertically between a tile unloading position coplanar with the plane of the press, and a loading and pressing position in which the base of the forming cavity is positioned below the plane of the press. Loading processes are known in which the soft mass consists of two or more overlying layers of materials of different characteristics. In these processes the mould cavity is loaded in at least two stages. In a first stage a layer of material generally forming the tile base is deposited in the mould cavity, followed by depositing on this first layer a layer of material forming the treadable (visible) part of the tile. In these processes the base of the mould forming cavity must also be able to be positioned in an intermediate position, between the unloading position and pressing position, to enable the second layer of material to be deposited. The loading systems disclosed above are disclosed by EP 0 444 730. FR 1 501 676 discloses a method for loading a soft mass into the forming cavity of a ceramic mould consisting of at least two overlying layers of powder material having different characteristics comprising the steps of depositing a first layer, compacting said first layer by the upper punch of the press, depositing the second layer and carry out the final compaction of said two layers, wherein the compacting means of the first layer are independent from the loading means of the said soft material, and therefore prevent said loading means to load the mass in only one to and fro movement of the carriage. The known loading systems have drawbacks which it is the intention of this invention to eliminate. A first drawback is the need to position the base of the forming cavity in an intermediate position in which the second layer of material is deposited. Moreover with known loading systems it is not possible to achieve a programmed distribution of the upper powder layer such as to define veining or a desired design on the tile surface. An object of the invention is to provide a mould loading process and the relative implementation means which enable tiles to be formed consisting of a multi-layer soft mass without the need for the intermediate positioning of the base of the forming cavity. A further object of the invention is to obtain the distribution of the upper powder layer in accordance with a desired design. To achieve the indicated objects according to the invention, in the case of two layers, at least the first layer is partially compacted before the loading of the second (last) layer. Moreover, according to the invention, the compacting means can present a surface provided with reliefs which define, on the first layer, cavities corresponding to the design to be created by the second layer. The invention achieves the aforesaid objects by virtue of the technical characteristics defined in the claims. In order to better clarify the operational and constructional characteristics of the invention two preferred embodiments thereof are described hereinafter by way of non-limiting example, and illustrated on the accompanying drawings. Figure 1, Figure 2 and Figure 3 show a partly sectional side view of the plant of the invention during different operating stages. Figure 4 shows the section IV-IV of Figure 1. Figure 5 shows the section V-V of Figure 3. Figure 6 shows a detail of Figure 5. Figure 7 shows the view VII-VII of Figure 4. Figure 8 shows a partly sectional side view of a second embodiment of the invention. Figure 9 is an exploded view of the parts shown in Figure 8. Figures 1 to 7 show a ceramic press 1 of known type provided with a mould 2 comprising three cavities 3. On the feed side of the press there is positioned a loading carriage 4 which can traverse horizontally between a soft material loading position and an unloading position therefor, driven by the geared motor 60 via a connecting rod-crank mechanism 5. The loading carriage 4 consists of an outer frame 40 comprising, in its rear part, a usual loading compartment 41 provided with an internal dividing grid, its front part supporting a small hopper 42 as wide as the front of the press and provided with a usual opening and closure device 43. Between the small hopper 42 and the loading compartment 41, the frame 40 supports a number of rollers 44 equal to the number of forming cavities. Each roller 44 has a smooth rolling surface, is as long as one of the cavities 3, and is provided with idly mounted shafts 45 which can slide vertically within the slots 46. From Figure 7 it can be seen that the slots 46 are provided in the supports 47. The same figure also shows a known device 48 which enables the lowest position of the rollers to be adjusted. The shafts 45 can also be conveniently motorized in order to roll without sliding on the powder lying within the mould cavity during the carriage traversing movement. The front edge of the frame 40 is provided with a usual pusher and scraper 400 for unloading the formed tiles and for maintaining the surface of the press 1 clean, and to remove any excess material. To the rear edge thereof there is connected a flat plate 410 as wide as the frame 40 and arranged to close the lower mouth of the hopper 6 which lies above the loading carriage 4. The hopper 6 contains the tile base material, which is fed into said hopper 6 by usual feed means, such as a traversing distributor tube 8 sliding on suitable guides 9, as shown in Figure 4. To the left of the hopper 6 there is a second hopper 7, which contains the quality material forming the visible layer of the tile, and is provided with its own opening and closure device 70. For operating the plant drive and control means there is provided a microprocessor with relative program which controls the following operation. By feed means of known type, not shown on the accompanying drawings, the two powder mixtures to form the tile base and its upper part are deposited in the hoppers 6 and 7, in quantities such as to fill the forming cavities. Figure 1 shows the loading carriage in the completely withdrawn position. In this position the hopper 6 has already discharged the base material into the compartment 41, the hopper 7 discharging the material contained within it into the underlying small hopper 42. On termination of the loading of the soft powder material, the loading carriage.4 is advanced as shown in Figure 2. Said figure shows the loading carriage 4 in the discharge position. Specifically, the loading compartment 41 is positioned in correspondence with the forming cavity 3, the base of which is lowered to receive the material contained in the compartment 41. At this point the loading carriage 4 withdraws by virtue of the connecting rod-crank mechanism. During the withdrawal of the carriage 4 the rollers 44, being free to move vertically, compact the base material present in the cavity 3 under the action of its own weight, to create in this manner the space necessary for depositing the second layer of material. The amount by which the rollers are lowered is regulated by the means 48. This second layer is deposited by the small hopper 42. In this respect, when the small hopper 42 is positioned in correspondence with the edge of the forming cavities 3, the microprocessor causes the closure device 70 to open so as to discharge the second layer of powder material onto the layer of base material precompacted by the rollers 44. Any excess material is removed by the pusher with scraper 45. The invention is also able to form tiles with surface decorations. For this purpose the rolling surfaces of the rollers 44 merely need to carry shaped impressions, the depth of these impressions being equal to the distance between the plane of the press and the precompacted mass, ie it corresponds to the lowering of the rollers. In this manner, during the withdrawal of the carriage 4 the rollers 44 compact the base material to create relief designs, the projecting surfaces of which are coplanar with the plane of the mould, and consist of the base material deriving from the first layer, the second layer of material deposited by the small hopper 42 filling only the non-relief regions, to create the surface decoration. If the rollers 44 comprise depressed or projecting parts for creating the space to receive the decoration, the shafts 45 of the rollers 44 are preferably motorized. With reference to Figures 8 and 9, it should be noted that those means corresponding to the first embodiment are indicated by the same reference numerals. The side wall of the frame 40 of the carriage 4 carries on its outside a fixed pin 153 on which a gear wheel 151 is idly mounted, and comprises a seat for rotatably receiving a shaft 148. External to the frame 40 there is fixed on the shaft 148 the inner part of a free wheel device 150, the outer part of which is associated with a gear wheel 149. Between the wheels 151 and 149 there extends a toothed belt 152, the upper portion of which is secured by a clamp 156 to the fixed frame of the machine. On the inner side the frame 40 of the carriage 4 the shaft 148 idly receives a support 146 via the seat 154 provided therein, and on the other side of the support fixedly carries a gearwheel 147. A second seat in the support 146 receives the shaft 45 of the rollers 44, which fixedly carries a gear wheel 145 engaging the gear wheel 147. It should be noted that the gearwheels 145 and 147 have the same pitch circle diameter, the diameter of the smooth part of the roller 44 being equal to the pitch circle diameter of the gearwheel 149. The combination of the shaft 148, gearwheel 147, gearwheel 145, shaft 45 and support 146 form a gear transmission rocking about the axis of the shaft 148, which represents the motion input shaft. The support 146, which is free to rock about the axis of the shaft 148, comprises a foot 157 arranged to rest on one side of a right-angled bracket 158 rocking about the axis 159, and having its other side engaged with the rod of a cylinder-piston unit 160, the body of which is fixed by the bracket 161 to the frame 40. The body of the cylinder-piston unit is fixed by screwing the threaded shank 162, rigid with the body of the cylinder-piston . unit, into a threaded seat in the bracket 161. The extent by which the rod 162 is screwed in determines the position of that side of the right-angled bracket on which the foot 157 rests, and hence limits the lowering of the roller 44. It should be noted that when the carriage 4 advances below the press, the rod of the piston 160 is retracted, and hence the roller 44 is raised, whereas when the carriage withdraws in the direction of the arrow 163 the roller 44 is left free to descend to the maximum extent permitted by the resting of the foot 157 on the right-angled bracket 158. It should further be noted that the free wheel 150 drags the shaft 148 only during the return movement of the carriage, in the direction of the arrow 163.

Claims: A method for loading a soft mass into the forming cavities (3) provided in ceramic press moulds (2), said soft mass consisting of at least two overlying layers of powder materials having different characteristics loaded in a single to and fro movement of a reciprocating loading carriage (4) comprising a loading compartment (41), characterised by filling the mould cavity (3) with a first layer of powder material; and while withdrawing said carriage (4), compacting said first layer by at least a roller (44) acting by gravity, and depositing on said compacted layer a second layer of powder material in such a quantity as to complete the filling of the cavity (3) created by the roller (44) before pressing. A method as claimed in claim 1, characterised in that the constituent material of the first layer is compacted only in limited regions of its surface thanks to impressions carried by the roller (44), the depth of these impressions corresponding to the lowering of the roller (44). A method as claimed in claim 2, characterised in that the constituent material of the second layer fills only said depressions. An apparatus for loading a soft mass, consisting of at least two layers of material , into the forming cavity of a ceramic tile mould, comprising a loading carriage (4) driven by usual means (5) to reciprocate between a loading position and a discharge position for said soft mass, said carriage (4) being provided with a usual grid-type compartment fed by usual means (6) and arranged to receive from these a first layer of said soft mass and to deposit said first layer into the forming cavity (3), characterised in that said carriage (4) comprises a frame structure (40) in a position below said compartment which supports, in succession, at least a roller (44) for compacting in a controlled manner said first layer of soft mass within the mould cavity while with drawing said carriage, and a small hopper (42) for feeding a second layer of said soft mass directly into the mould cavity after the first layer has been compacted, the small hopper (42) being provided with a lower closure valve (43). An apparatus as claimed in claim 4, characterised in that said at least one roller (44) for compacting said first layer of soft mass is transversely arranged and free to move vertically guided by suitable supports (47, 146) and has a length virtually equal to the width of the forming cavity. An apparatus as claimed in claim 5, characterised in that said at least one transverse roller (44) is idle. An apparatus as claimed in claim 5, characterised in that said at least one transverse roller (44) is motorized. An apparatus as claimed in claim 5, characterised in that said suitable supports (47, 146) are provided with a usual screw adjustment device (48, 162), which limits the lowering of the roller (44). An apparatus as claimed in claim 4, characterised in that said roller (44) has a smooth rolling surface. An apparatus as claimed in claim 4, characterised in that said roller (44) has a rolling surface provided with depressions of an extent equal to the extent of lowering of the roller . An apparatus as claimed in claim 7, characterised in that the shaft (45) of said at least one roller (44) is connected via a gear transmission (145, 147) to a gearwheel (149) which has the same diameter as said at least one roller (44) and is constrained to rotate with a peripheral speed equal to the traversing speed of the carriage (4). An apparatus as claimed in claim 11, characterised in that . said gearwheel (149) which is constrained to rotate with a peripheral speed equal to the traversing speed of the carriage (4) is engaged with the input shaft (148) of the gear transmission via a freewheel device (150) which drags it only during the withdrawal movement of the carriage. An apparatus as claimed in claim 11, characterised in that said gear transmission (145, 147) is located on a support (146) free to rock about the axis of the motion input shaft (148). An apparatus as claimed in claim 13, characterised in that said support (146) is associated with a cylinder-piston unit (160) which induces its rocking movements starting from a lower stop point, the level of which can be adjusted by an adjustment screw (162).

Inventors: BERTOLINI MARIO, CAVAZZONI GIANPAOLO, BERTOLINI, MARIO, 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: B28B3, B28B13