EP2050549A2

EP2050549A2 - An apparatus for continuously feeding powders in manufacturing of ceramic tiles

Info

Publication number: EP2050549A2
Application number: EP08166363A
Authority: EP
Inventors: Stefano Scardovi; Silvano Valli
Original assignee: Sacmi Imola SC
Current assignee: Sacmi Imola SC
Priority date: 2007-10-15
Filing date: 2008-10-10
Publication date: 2009-04-22
Also published as: EP2050549A3; ITRE20070108A1

Abstract

An apparatus for continuously feeding powders in manufacturing of ceramic tiles, which powders form a layer (200) of coloured powders upon a continuously advancing base layer (100), the layer (200) being fed by a prism-shaped hopper (4) containing many-coloured powders in a pre-ordered arrangement. The appartus comprises means for creating troughs in the base layer (100) before the base layer (100) receives the layer (200) of coloured powders. The means comprise a screed (10) of the base layer (100), comprising a sheet (110) of plastic or elastomer material, a powder-contacting edge of the screed (10) exhibiting a non-rectilinear outline which is continuously modifiable in a vertical plane.

Description

The invention relates to the sector of methods and plants for creating layers of ceramic powder destined to be pressed and comprising at least two layers, a base layer of monochrome powder and an upper layer of variously coloured powders, in order to create the graphic effect of the final decoration which will appear on the tile.
In particular the invention concerns plants for preparing coloured powders in order to form ceramic tiles or slabs which are described in the Italian patent application RE2005A000086 in the Applicant's name.
The plants comprise a first vertical hopper which is situated above a moving horizontal plane onto which the hopper discharges a base layer of monochrome ceramic powders.
Downstream of the first hopper, a second hopper discharges a second layer of coloured powders onto the base layer, which second layer is destined to constitute the visible decorated surface of the tile or slab.
The second hopper has the shape of a parallelepiped, with a first pair of surfaces, i.e. the lateral surfaces, being parallel to the direction of advancement of the base layer and a second pair of surfaces, the front and rear surfaces, being arranged at right angles to the direction of advancement of the base layer. The distance between the front surface and the rear surface is substantially the same as the thickness of the layer of coloured powders to be deposited on the base layer of powder. The coloured powders are loaded through the upper opening and discharged through the lower opening, which is situated at a distance from the base layer corresponding to the thickness of the layer. The powders are loaded into the second hopper in a pre-ordered way by appropriate feeder means, which are of a known type, and subsequently the powders fall continuously onto the underlying advancing base layer. In this way, a layer of coloured powders is formed on the base layer, the layer reproducing generally speaking the same pre-ordered arrangement of the powders in the second hopper.
To improve the aesthetic effect of the slab or tile by modifying the effect when so desired, the prior art provides means which create cavities in the base layer before the second layer is deposited on it.
These means are constituted by a transversally and horizontally mobile scoop element, which is arranged at the output of the first hopper, and which sinks an irregular trough into the base layer of powder.
Although the known device has provided satisfactory results, it has a number of drawbacks due to that fact that the trough which the scoop element makes exhibits a section having a constant width, which is the same as the width of the scoop, and the trough cannot be associated to other troughs which are adjacent to, and possibly intersect, the first trough.
The aim of the present application is to obviate the above-mentioned drawbacks by means of a simple, rational solution.
The aim is achieved by the device in accordance with claim 1.
The other dependent claims delineate preferred and particularly advantageous embodiments of the invention.
Further characteristics and advantages of the invention will emerge from the description below, which is provided as a non-limiting example, with the aid of the appended figures of the drawings, in which:

figure 1 shows a schematic vertical section view of a plant for altering the arrangement of the powders forming a layer for producing ceramic tiles or slabs, in accordance with the invention;
figure 2 shows a front view of the screed device;
figure 3 is an enlarged detail of figure 2;
figure 4 shows a section view along plane IV-IV of figure 3;
figure 5 shows a section view along plane V-V of figure 2.

In the figures, a discharge mouth of a first hopper 1 is closed by a hatch 11, which is activated by a jack 12.
The monochrome powders contained in the first hopper are discharged over the moving plane 2 in the direction of the arrow in figure 1 and suitably levelled by means of a screed 10, which adjusts the thickness of the first, or base layer.
A second vertical hopper 4 is arranged above the plane 2 upon which the first, base layer advances.
The hopper 4 has the shape of a parallelepiped with a first pair of surfaces, called lateral surfaces, which are arranged parallel to the direction of advancement of the moving plane 2, and a second pair of surfaces, 4a, 4b, front and rear respectively, which are arranged at right angles to the direction of advancement of the moving plane 2. The hopper is loaded with coloured powders through an upper opening 41 by means of appropriate feeder means, which for the sake of simplicity are not shown, the coloured powders being arranged in a pre-ordered way and continuously gravity-fed through a lower opening 42, the distance from the base layer 100 transported on the plane 2 to the opening 42 being equivalent to the thickness S of the layer 200 of coloured powders to be deposited.
Preferably, the distance B between the front surface 4a and the rear surface 4b of the hopper 4 is equivalent to the thickness S of the layer 200 of coloured powders to be deposited on the base layer 100.
In this way, a layer 200 of coloured powders can be formed superficially on the continuously advancing base layer 100, reproducing a same pre-ordered arrangement as the coloured powders contained in the hopper 4. In particular, the pre-ordered arrangement of the coloured powders forming the layer 200 reproduces the typical veining found in natural stone.
In the invention, the levelling edge of the screed 10 which levels the material exiting from the first hopper exhibits a non-rectilinear and modifiable outline in the vertical plane.
To this end, the screed 10 comprises a sheet 110 of elastomer or plastic material supported by means which can locally deform the sheet in the direction of advancement of the material, the deformation giving rise to local variations in the height of the sheet and consequently modifying the outline of the screed edge in the vertical plane.
For example, the sheet is gripped between a first continuous plate 101, which is adjacent to the mouth of the first hopper 1, and at least a second preferably flexible plate 102, which is supported opposite the plate 101 by a bar 105.
A series of bolts 103 screwed into the bar 105 pushes the plate 102 against the sheet 110.
The bolts could be replaced by other equivalent means, for example hydraulic pistons.
The second flexible plate 102 can advantageously be replaced by an alignment of rigid plates which are independent of each other.
Varying the degree of tightness of the bolts 103 gives rise to deformations of the sheet 110, by virtue of which deformations the lower profile of the sheet 110 assumes a configuration which is undulated with continuity, without sharp variations to its lower profile.
Good results have been obtained using a sheet made of the synthetic elastomer material known as VULKOLLAN^® which is produced by BAYER. The sheet conveniently has a thickness/height ratio of between 1:10 and 1:6.
Thus depressions or troughs 20 are created on the upper surface of the powder of the base layer, alternating with areas in relief which vary continuously in amplitude, depth and direction.
At least some of the bolts 103 can be activated by a preferably electric actuator device which is provided with electronic control means, enabling the profile of the sheet 110 to be varied at the bolt.
The same results can be obtained by using hydraulic pistons as the tightening means.
The actuator means are of a known type, thus are not represented , since the actuator means can easily be implemented by the person skilled in the art.
The screed 10 is height-adjustable; to this end, the bar 105 is supported by two lateral jacks 106 which are connected by the shaft 108 such as to be activated simultaneously by a single handle 107.
The troughs 20 and the relative zones in relief alter the pre-ordered arrangement of the coloured powders forming the layer falling on the first layer from the second hopper 4, which layer would otherwise reproduce the same arrangement of the powders which is present in the hopper 4.
In fact, if the surface of the first layer is flat, the powders 33 fall at a constant speed along the front of the screed.
Instead, if there is a trough 20, when the trough 20 reaches the outlet opening 42 of the coloured powders, the speed of fall of the portion of coloured powders above the trough increases in comparison with the speed of the surrounding powders.
This happens because the presence of the trough 20 requires a larger amount of powders 33 compared with the surrounding flat zones of the base layer.
This phenomenon alters the arrangement of the powders falling from the hopper 4, which alteration is transferred and reproduced on the powders of the second layer being deposited on the base layer, thus modifying the graphic aspect of the decoration.
In order to obtain variations giving the desired effect, it is necessary to change the point at which the trough 20 is created, and the size of the trough 20, by modifying, continuously or at intervals, the degree of tightening of the bolts 103 or other tightening means which have been adopted.
As emerges from the description, the system for altering the arrangement of the powders forming a layer for creating ceramic tiles or slabs according to the invention makes it possible to satisfy these requirements and to obviate the drawbacks mentioned in the preamble of this description.

Claims

An apparatus for continuously feeding powders in manufacturing of ceramic tiles, which powders form a layer (200) of coloured powders upon a continuously advancing base layer (100), the layer (200) being fed by a prism-shaped hopper (4) containing many-coloured powders in a pre-ordered arrangement, means being provided which create troughs in the base layer (100) before the base layer (100) receives the layer (200) of coloured powders, characterised in that the means comprise a screed (10) of the base layer (100), comprising a sheet (110) of plastic or elastomer material, a powder-contacting edge of the screed (10) exhibiting a non-rectilinear outline which is continuously modifiable in a vertical plane.
The apparatus of claim 1, characterised in that the sheet (110) is gripped between means which give rise to local deformations in the direction of a thickness of the sheet (110), which means cause variations in a profile of a powder-contracting edge of the sheet.
The apparatus of claim 2, characterised in that the sheet (110) is gripped between a first plate (101) and a second plate (102) by a series of adjustable tightening means.
The apparatus of claim 3, characterised in that the means are bolts a fastening of which can be adjusted.
The apparatus of claim 3, characterised in that the means are hydraulic pistons.
The apparatus of claim 1, characterised in that the sheet is made of an elastomer material known as VULKOLLAN^®.
The apparatus of claim 3, characterised in that the first plate (101) is rigid.
The apparatus of claim 3, characterised in that the second plate (102) comprises a series of consecutive adjacent segments.
The apparatus of claim 3, characterised in that the second plate (102) is flexible.
The apparatus of claim 1, characterised in that a ratio between a thickness and a height of the sheet (110) is between 1:6 and 1.10.
The apparatus of claim 2, characterised in that at least a part of the tightening means is activated by a servo mechanism (104) controlled by an electronic processor.
The apparatus of claim 1, in which a distance (B) between a front surface (4a) and a rear surface (4b) of the second hopper (4) is equivalent to a thickness (S) of the layer of powders (200) to be transferred onto the base layer (100).
The apparatus of claim 12, in which a distance between an outlet opening (42) of the hopper (4) and the base layer (100) is equivalent to the thickness (S) of the layer of powders (200) to be transferred onto the base layer (100).
The apparatus of claim 1, wherein the screed (10) is height-adjustable and is supported by two lateral jacks (106) which are connected by a shaft (108) in order to be activated simultaneously by a single handle (107).
A screed for creating troughs in a continuous layer of powders advancing on a plane, characterised in that it comprises a sheet (110) of plastic or elastomer material gripped between means for modifying a vertical height of the sheet (110), by which modifying a profile of a powder-contacting edge in a vertical plane is varied.
The screed of claim 12, characterised in that at least a part of the means for modifying is activated by an actuator controlled by an electronic processor.
The screed of claim 15, characterised in that the means for modifying are bolts with adjustable tightening.
The screed of claim 15 characterised in that the means for modifying are hydraulic pistons.