MARTINELLI, Paola (Via Montegibio 2/c, Sassuolo, I-41049, IT)
| CLAIMS 1. System for loading and depositing layers of dusts into a press for ceramic products, comprising a first device (13) for discharging dusts and a second device (14) for discharging dusts, receiving from the first, the first device (13) being external with respect to the press and the second device (14) sliding horizontally moving between a discharge position beneath the first device and a path for discharging into the press, characterized in that the first and the second discharge devices each have a discharge mouth (21) which is fed through an opening (22) provided with a "guillotine" interception shutter (23) which is controlled to slide on a substantially vertical plane containing an opening (22) . 2. System according to claim 1, characterized in that the first device (13) moves vertically to position its discharge mouth against dusts reception container (26) of the second device (14) at a loading position. 3. System according to claim 1, characterized in that feeding means (17) are present which discharge the dusts into the first device (13) . 4. System according to claim 3, characterized in that the feeding means employ a sliding feeding pipe (17) which enters into the dusts container (26) of the first device to convey the dusts therein. 5. System according to claim 1, characterized in that a pipe (25) upstream of the opening (22) has a tilted lower plane and a pipe (27) downstream is vertical towards the respective supply mouth (21) . 6. System according to claim 1, characterized in that the shutter has a lower edge which forms an acute angle (28) against the sliding surface. 7. System according to claim 1, characterized in that it comprises means (18) for loading a base mixture into the mould. 8. System according to claim 8, characterized in that the loading means (18) comprise a loading grid (19) controlled to slide between an external position with respect to the press and a position for discharging into a cavity in the press in the path passing beneath a hopper (20) for filling the grid. 9. System according to claim 9, characterized in that the second device (14) moves in a manner integral with the loading grid (19) and it is arranged in front of the grid in the press inlet direction. 10. System according to claim 1, characterized in that it comprises a plurality of pairs of said first and second discharge devices (13, 14), for depositing a plurality of layers of dusts into one or more cavities. |
The present invention refers to a system for loading mixtures (raw materials) onto presses for pressing ceramic products, such as tiles, made from ceramic material with two or more layers .
Systems for loading presses for ceramic products generally comprise a trolley sliding horizontally inside and outside of the press, which is loaded with ceramic dust by a suitable feeder. In order to make thin surface layers, the trolley comprises a small discharge device which is actuated while the cart is running above the pressing cell, the cell generally being already filled with the main dust layer through a loading grid, also fixedly connected to the trolley. Usually, the discharge device is in turn loaded by a further discharge device, stationary outside the press, thus making a two stage discharge system.
Two stage systems exist, for example, with discharge devices having shutters which rotate around a horizontal axis revealing a downward facing discharge opening. One problem is to carry out the discharge in a sufficiently uniform manner. Indeed, known systems do not allow the layer to be measured out in a sufficiently controlled manner, especially at the beginning and the end of the depositing, and, often, there are local thickenings on the surface of the tile to be formed thus consequently affecting the quality of the product negatively.
Moreover, for known systems the lack of precision at the beginning and at the end of the discharge causes dusts to be dispersed outside the cell. Together with such dispersion, there is also the dispersion of dusts into the environment due to the type of discharge from one stage to the next. All of this leads to a variety of problems, for example, in the case of mixtures which are particularly valuable and/or which must not be dispersed into the environment, due to cost and/or environmental pollution problems. The dispersion of the dusts also leads to product quality problems. Indeed, the dispersed dusts can pollute other mixtures which may be present (for example, the mixture which will be used to create the underlying layer and which will form the actual body of the tile) .
The general purpose of the present invention is that of avoiding the aforementioned drawbacks by providing a loading system which allows a low dispersal of dusts to be obtained, avoids accidental spilling, has a precise discharge and deposits homogeneous and constant layers, even ones having a low thickness. In view of such a purpose it has been thought to make, according to the invention, a system for loading and depositing layers of dusts into a press for ceramic products, comprising a first device for discharging dusts and a second device for discharging dusts received from the first, the first device being external with respect to the press and the second device sliding horizontally moving between a loading position beneath the first device and a path for discharging into the press, characterized in that the first and the second discharge devices each have a discharge mouth that is fed through an opening provided with a "guillotine" interception shutter which is controlled to slide on a substantially vertical plane containing the opening .
In order to clarify the explanation of the innovative principles of the present invention together with its advantages with respect to the prior art, hereafter, with the help of the attached drawings, we shall describe a possible embodiment applying such principles.
In the drawings : - figure 1 represents a schematic and sectioned side view from the top of a system for loading a press according to the invention;
- figure 2 represents a schematic sectioned view of a detail of the system of figure 1; - figure 3 represents a partial and perspective schematic view of a system according to the invention with a plurality of loading devices .
With reference to the figures, figure 1 schematically shows a system, generically indicated with reference numeral 10, for loading and depositing layers of dusts in a press 11 for tiles and similar ceramic products. In particular, the system is suitable for depositing thin layers, for example, for applying dry glaze .
The system comprises at least one distributing module 12 formed by a first device 13 for discharging dusts into a second device 14 for discharging dusts.
The first device 13 is external with respect to the press, whereas the second device 14 can slide horizontally moving between a loading position beneath the first device and a path for discharging into a pressing cell 30 in the press. The device 14 is slightly raised from the dusts sliding plane and it has the exact same length (transversal to the press entry movement) as the cell which it must load. Advantageously, the first device 13 moves vertically, through actuators 15, to position its discharge mouth against the dusts reception container of the second device at a loading position. The first device 13 is in turn supplied with dust thanks to feeding means 17 which discharge the dusts into the container of the first device. Such feeding means advantageously use a sliding feeding pipe 17 which enters into the dusts container of the first device to insert the dusts therein and that slides along the container to deposit the dust along its entire extension.
Such means are substantially of the known type and can easily be imagined by a man skilled in the art. Thus, they shall not be shown or described any further. The horizontal movement of the second device is obtained through a suitably motorized trolley structure 18. Advantageously, such a structure, as well as moving the device 14 backwards and forwards, it also supports and moves a loading grid 19 which is supplied with dusts by a hopper 20 to load the mixture base into the mould. The grid is controlled to slide between an external position with respect to the press and a position for discharging into the cell of the press, passing beneath the hopper for filling the grid. Advantageously, the second device 14, which in practice moves integral with the loading grid, is arranged at the front of the grid in the press inlet direction.
The two dusts discharge devices are substantially similar, apart from their sizes. Indeed, the upper one has the function of being a dust ' reservoir and it tends to have a greater capacity, whereas the lower one, which has the function of being a distributor of the material in the mould cavity, is less capacious, so as to be smaller and to be able to enter the press easily. The distributor device 14, is supplied when needed by the reservoir device 13, in general when the trolley is inactive. For example, a suitable known probe can be foreseen to record the quantity of mixture present within the distributor and to control the filling. Figure 2 shows the structure of one of the two dusts discharge devices in greater detail (the other one in substance varies only for the size of the dusts container) .
The discharge devices each have a discharge mouth 21 (advantageously open in a horizontal plane) which is fed through an opening 22 open in a substantially vertical plane, as wide as the mould and provided with a "guillotine" interception shutter 23 which is controlled to slide by a suitable actuator 24 on the vertical plane containing the opening 22. The pipe 25 upstream of the opening 22 has a lower plane tilted downwards between the container 26, which receives the dusts, and the opening 22. The inclination is such that it ensures efficient sliding of the dusts. The pipe 27 downstream of the opening, on the other hand, is vertical towards the respective supply mouth, it is as wide as the mould and the shutter slides in it. As can be clearly seen in figure 2, the shutter advantageously has a lower edge which forms an acute angle 28 against the sliding vertical surface 29. This allows the sprinkling of mixture to be "cut off", during the closure, without causing the dust particles to be crushed, which would lead to the formation of flakes. When the shutter is in its closed position (shown in figure 2) its end part is lower than a small portion with respect to the tilted pipe 25, so as to ensure that the shutter is perfectly sealed. The pipes 25 and 27 and the sliding seat of the shutter can be advantageously obtained in a single metallic block suitably machined through mechanical chip removal. This ensures that the structure, to which the dusts container is applied, is simple and robust.
Thanks to the use of vertical shutters and to the aforementioned structure, it has proven to be easy to create, a thin and controlled sprinkling of a mixture (in the granular state), along the entire length of the cell. The density of the sprinkled mixture (or rather the quantity of deposited material) , is not affected negatively by the quantity of mixture present in the distributor. Moreover, flakes are not formed in the mixture, which could partially obstruct the system itself or, in any case, give the end product a poor appearance .
There has also been a reduction to the minimum of the rising of dust clouds of mixture, which when deposited could pollute other possible mixtures, thus creating not only aesthetic problems but also technical ones, during the subsequent manufacturing stages and which in any case constitute a waste and therefore also an economic loss, due to the high costs of such mixtures, as well as being potentially harmful.
Thanks to the system described it is possible to obtain high quality tiles, saving on the use of precious raw materials and reducing the dispersion of thin dusts into the environment. Moreover, the system is easy to implement and it has great flexibility, therefore, for example, it is suitable for manufacturing small batches having the same format, but having different color or shade.
It should be noted that the creation of the sprinkled mixture, in the case in which thin layers are desired to be deposited, allows the material to be directly deposited above the cavity of the mould, or rather it is not necessary for the mould to make an intermediate fall, in order to create a compartment in which to receive the new mixture layer (as it is known, this movement of the mould can cause the dusts already deposited to be mixed again, which is not pleasing from an aesthetic point of view in the end product) .
In order to reduce to the minimum possible defects of dust diffusion on the edges at the beginning and end of the mould, the opening and the closing of the shutters is easily controlled so they occur exactly at the beginning and at the end of the cell itself.
The movement of the shutter of the upper device 13 can simply be of the open-closed type, whereas for the shutter of the lower device 14 the movement can advantageously be of the continuous type, with the option of partialising the opening, so as to be able to precisely adjust the quantity of dusts in outlet. Otherwise, the deposited quantity can be adjusted, exclusively through the passing speed of the trolley over the cell.
All of this can be obtained with a suitable and per se known electronic control system of the movement of the trolley and of the shutters, easily imagined by a man skilled in the art and therefore it shall not be shown or described in detail. The movement of the trolley can advantageously be obtained with step-by-step motors (or equivalent system) . In figure 3, a possible structure of the system is partially visible in a schematic manner, according to the invention, comprising a plurality of pairs of distributor modules each formed by the aforementioned first and second discharge device 13 and 14. In particular, in such a structure there are as many rows of modules as there are cells (that is to say, the "outlets" from the mould) . There can also be one grid (not shown in figure 3) for each cell.
In the case in which the mould is replaced with another one having a different number of outlets, the set of modules can easily be replaced with a new one, suitable for the new mould (new cell format and/or number of cells) .
Again, as shown in figure 3, it is also possible to mount many modules in series, one after each other, so as to be able to load many layers of mixture, or when the mould has many aligned cavities, to obtain tiles having different colors or shades in the various outlets of the mould or, even, to use a different module for the different cells of the mould, for example for a mould with two outlets, the first outlet can be loaded by using the respective first module and the second outlet with the respective second module (or vice versa) , varying such a selection (even from press cycle to press cycle) acting on the machine. Since, in some cases, it is necessary for the minimum distance between the last module and the grid behind it to be at least equal to the length of the cell ( for example, when it is necessary for the mould to make an intermediate fall, to receive a thick layer of mixture) , the grid itself can be equipped with a known movement device able to bring it closer to the module farthest back, in the case there is no longer the aforementioned necessity, thus obtaining a shortening of the journey of the trolley and of the production cycle.
Such a solution can also be convenient when there are many modules in series and it has been decided to eliminate some. It shall then be possible to use the space now vacant.
At this point it is clear how the purposes have been achieved, by providing a system for loading which is simple, flexible and efficient. Of course, the description above of an embodiment applying the innovative principles of the present invention is given as an example of such innovative principles and therefore must not be taken to limit the scope of protection claimed hereby .