EP1225016A2

EP1225016A2 - Method for loading ceramic tile forming moulds, relative means for its implementation, and tiles obtained thereby

Info

Publication number: EP1225016A2
Application number: EP01202861A
Authority: EP
Inventors: Carlo c/o L.B.-Officine Giglioli
Original assignee: L B Officine Meccaniche SpA
Current assignee: L B Officine Meccaniche SpA
Priority date: 2001-01-22
Filing date: 2001-07-27
Publication date: 2002-07-24
Also published as: ITRE20010002A0; EP1225016A3; ITRE20010002A1

Abstract

A method for loading ceramic moulds presenting at least one forming cavity, comprising, for each complete loading cycle, the following operating steps: in a supply station, preparing a powder layer consisting of at least two masses of differently coloured powder materials, and presenting in plan view a shape at least equal to that of said at least one forming cavity, and transferring said layer onto said at least one forming cavity, and comprising the operating step of displacing in plan view, relative to said at least one forming cavity, at least a portion of said layer.

Description

This invention relates in a totally general manner to the manufacture of ceramic tiles, and in particular concerns a method for loading powder materials into the relative forming moulds.
The invention also relates to the means for implementing said method, and the products obtained thereby.
The ceramic tile manufacturing sector is known to be constantly seeking new and original motifs, and in particular decorations reproducing the appearance of natural stone, such as marble, which is known to present veining and elongate striations of various shapes and colours.
The characteristic appearance of said stone, such as the said marble, derives mainly from the randomness presented by the shape, the length, the distribution, the colour and the shading of said veining and elongate striations.
Decorative motifs reproducing said appearance typical of marble can be obtained by the modern ceramic technology involved in the manufacture of fine porcellainized sandstone, which is well known to the expert of this sector, and will therefore not be described in detail.
It is sufficient to state that the systems used so far within the context of said technology have not yet been able to produce tiles which satisfactorily reproduce the special characteristic of a natural stone such as marble, i.e. the said randomness with which its veining, or rather its various constituent elements, are presented.
The main object of the present invention is to provide a loading method which is of simple implementation, and by which the tiles leaving the forming mould after each pressing present gradually differing appearances, i.e. veining which differs each time in at least one of the following details: shape, length, distribution, colour, shading, in such a manner as to reproduce the randomness with which such veining is presented in natural materials such as marble.
Another object of the invention is to provide means for implementing said method within the context of a simple, rational, reliable, long-lasting and low-cost construction.
Said objects are attained by virtue of the characteristics indicated in the claims.
The method of the invention is based on the technique by which for each complete loading cycle there is created, typically within a containing grid, a powder layer consisting of at least two partly mixed masses of different materials having different characteristics, typically at least two powders of different colour, and to transfer said layer onto a usual ceramic mould having at least one forming cavity, said layer depositing by gravity.
According to the invention, at each individual complete loading cycle, at least one portion of said layer is displaced in plan view relative to said at least one forming cavity.
In particular, said displacement is advantageously effected randomly cycle by cycle.
Moreover said displacement can be coarse or fine.
The objects of the invention are attained by the aforesaid method in that after each pressing the tiles present veining or striations which gradually differ, again in consideration of the fact that the parameters which govern the supply of the powders to said containing grid can be regulated, either in combination with said displacement, or not.
The means according to the invention, which are described in detail hereinafter, comprise a usual carriage driven with reciprocating movement and presenting a powder containing grid, in which the position of at least one constituent element of the grid and/or the shape of said at least one element can be adjusted relative to the carriage at discretion, either automatically or not.
The characteristics and merits of the invention will be apparent from the ensuing detailed description thereof given with reference to the figures of the accompanying drawings, which illustrate by way of non-limiting example a particular embodiment of the means for implementing the method of the invention.
Figure 1 is a side view showing the means of the invention associated with a usual loading carriage of a likewise usual ceramic mould.
Figure 2 is a section on the line II-II of Figure 1 on a smaller scale.
Figure 3 is a part of Figure 2 showing the configuration of the carriage when in its position of maximum withdrawal for collecting the powders.
Figure 4 is a view similar to that of Figure 2, showing one of the possible configurations which the loading carriage can assume during deposition of the powders into the cavity of the forming mould.
Figure 5 is a part of Figure 4 showing the loading carriage alone, on an enlarged scale.
Figure 6 is a view similar to the preceding, showing another possible configuration of the loading carriage.
Figure 7 is a part of Figure 5 on an enlarged scale, showing a further configuration of the carriage.
Figure 8 is a schematic plan view showing a different method of driving the grid.
Said figures, and in particular Figures 1, 2 and 4, show a usual ceramic press 1, on the bed of which there is positioned a mould 2 having a single forming impression or cavity 3.
Said mould 2 is of usual type and will therefore not be described in detail, it being able to present any number of cavities 3 as is well known.
The system for loading the powders into the mould 2 is positioned on the front side of the press 1, as is usual.
Said system comprises a structure 4 supporting a horizontal table 5, coplanar with the upper mouth of the cavity 3, and on which there slides a usual loading carriage 6 driven with reciprocating movement.
The carriage 6 comprises a grid 7 which moves between an advanced position in which it overlies said cavity 3 (see Figures 4 and 5), and a withdrawn position in which it receives the powder mass to be discharged into said cavity 3 (see Figures 1 to 3).
As can be seen from Figure 1, the grid 7 is closed lowerly by the table 5 along which the carriage 6 slides, except for the region in which it overlies the cavity 3.
Above that region of the table 5 occupied by the grid 7 when in its withdrawn position, there is a hopper 8 lowerly provided with a narrow elongate mouth, the length of which is positioned transversely to the sliding direction of the carriage 6.
Said mouth is inclined in the transverse direction as shown, with its lower longitudinal generator practically flush with the upper face of the grid 7, and is intercepted by a shutter 9 under the control of a cylinder-piston unit 10.
The hopper 8 is supported by an overlying frame 80, and communicates with a powder arrival chamber 81 at which a series, namely three in number in the illustrated example, of flexible conduits 83 terminate for supplying differently coloured materials in powder form; a flow regulator valve 88 is positioned where each conduit 83 opens into the chamber 81.
Said chamber 81 is provided with at least one level probe 82, said flexible conduits being able to slide in known manner relative to the upper mouth of the chamber 8.
The frame 80 is also arranged to move parallel to the sliding direction of the carriage 6 synchronously with the travel of this latter, to discharge the powder mass into the grid 7 by opening the shutter 9.
No further operational or constructional details of the powder supply system will be given as they are not relevant to any characterising part of the invention.
It is sufficient to state that, for example, differential production of veining decorations, constituting the subject of the present invention, can be achieved either by regulating the degree of opening of at least one valve 88, or by excluding one of said flexible conduits, or by varying the speed with which the material flows through one or more of said flexible conduits 83, or by changing the type of powder served by the same conduits 83, in combination with the characteristic elements of the loading system described hereinafter.
As best seen from Figures 2 to 7, according to the invention the grid 7 is connected to the carriage 6 in such a manner as to be able to be rotated in the two opposing directions about the vertical barycentric axis 99 of its plan profile.
Said carriage 6 consists essentially of a rectangular frame, of which the front cross-member carries a pusher 98 for discharging the formed tiles, the longitudinal members each being provided internally with a front ledge 97 and a bush 96.
The bush 96 is traversed by a slidable rod 95 which at its front end is hinged to a connecting bar 94, and at its rear end is coupled to a linear actuator 93 fixed to the frame of the carriage 6. At their other end the two connecting bars 94 are connected together by a rocker arm 92 behind which the grid 7 is fixed.
The hinge pins between the rods 95 and connecting bars 94, and between these latter and the rocker arm 92, are received in respective slots 192 and 292 in said ledges 97, of which the former 192 are rectilinear and the latter 292 are arched, with their centre of curvature at 99.
It should be noted that in the illustrated example the swing of the grid 7, in one direction and the other about its neutral position of Figures 2 and 3, is about 10°, but this does not constitute a limit.
It should also be noted that the two linear actuators 93 operate in phase opposition, i.e. while one is elongating the other is shortening correspondingly.
In the variant of Figure 8, to cause the grid 7 to rock, the respective driving rocker arm 92 presents two end pins 75 which are slidingly received within respective transverse rectilinear slots 74 provided in two longitudinal sliders 73 operated by the linear actuators 393.
There are also provided two arched shoes 72 which are fixed to the sides of the grid 7, and engage the rods 95 by a rolling engagement.
The grid 7 comprises a peripheral frame in the form of a rectangular rim the aperture of which has dimensions exceeding those of the cavity 3.
Said aperture is divided into a plurality of compartments by a multiplicity of sinuous baffles 77.
The baffles 77 present different patterns, and slightly different and/or variable thicknesses, some of them connecting together two parallel sides of the rim, others connecting together two consecutive sides of the said rim, and still others being interposed between two adjacent baffles 77.
According to an advantageous characteristic of the invention, at least one of said baffles 77 is elastically deformable in the horizontal plane, and has at least one end not rigidly connected to the perimetral rim of the grid 7, but joined to it via a cylinder-piston unit 76.
Said (at least one) cylinder-piston unit 76 and said actuators 93 are under the control of the central regulating and control unit of the press 1 and carriage 6, which also controls the hopper 8 and the relative accessories.
In addition, according to the invention, in the electronic memory devices of said central control unit there is stored a program or procedure based on a random relationship for adjusting the members used to obtain the veined decoration, mainly the actuators 93 and the cylinder-piston unit 76, but also, as stated heretofore, the accessories of the hopper 8.
For the purposes of the invention, said procedure is activated at each loading cycle, said randomness involving one or more of said members either for each loading cycle, or not.
Moreover the (one or more) adjustments can be made coarsely or finely, but always randomly.
The said adjustments are made automatically, however the operator is able to intervene, for example by means of a keyboard 33 (Figure 1) for entering data, in order to modify or vary at discretion all or part of said random procedure.
Finally, it should be noted that the aforegoing is also valid for grids 7 provided to serve moulds 1 having more than one forming cavity 3.
The implementation of the method is evident from the aforegoing.
Each time the grid reaches the end of its withdrawal travel, it lies in the aforestated neutral position, i.e. with the sides of its peripheral rim parallel to those of the carriage 6, where it receives from the hopper 8 a layer of powder comprising differently coloured masses mixed together, at least in the limiting layers.
During this stage the variable-shape baffle 77 connected to the cylinder-piston unit 76 can be in any one of its possible configurations.
Moreover, seeing that the capacity of the grid 7 is known to be greater than that of the forming cavity 3, there is no reason why during the deposition of said layer the grid should not be at least slightly rotated (in one direction or the other) about said neutral position.
When the carriage 6 slides towards the mould 1, as already stated at least one of the parameters governing the operation under way is varied randomly in accordance with said program, and with the possible intervention of the operator controlling the operation.
There is nothing to prevent the shape of said variable-shape baffle 77 being adjusted always randomly at the time of depositing the powder into the cavity 3.
Said randomness achieves the required results, i.e. tiles which after each pressing present differently veined ornamental motifs, hence reproducing that typical of natural stone, such as marble.

Claims

A method for loading ceramic moulds presenting at least one forming cavity, comprising, for each complete loading cycle, the following operating steps:

in a supply station, preparing a powder layer consisting of at least two masses of differently coloured powder materials, and presenting in plan view a shape at least equal to that of said at least one forming cavity; and

transferring said layer onto said at least one forming cavity, characterised by comprising the operating step of displacing in plan view, relative to said at least one forming cavity, at least a portion of said layer.
A method as claimed in claim 1, characterised in that said displacement is effected cycle by cycle in a random manner.
A method as claimed in claim 2, characterised in that said random displacement takes place automatically.
A method as claimed in claim 2, characterised in that said random displacement takes place by remote manual control.
A method as claimed in claim 2, characterised in that said random displacement consists of a combination of automatic operations and manual commands.
A method as claimed in claim 1, characterised in that the operating parameters of said supply station are varied randomly, either in combination with said displacement or not.
Means for implementing the method claimed in claims 1 to 6, comprising a loading carriage presenting a powder retention grid and driven with reciprocating rectilinear movement between a withdrawn position in which it disposes the grid below at least one hopper for supplying a powder mass consisting of at least two partially mixed materials having different characteristics, and an advanced position in which it disposes the said grid above a mould having at least one forming cavity, characterised in that at least one constituent element of said grid is provided with means for regulating its position relative to the carriage.
Means as claimed in claim 7, characterised in that said at least one constituent element is the grid overall, said regulating means consisting of a linkage system arranged to rotate said grid about the barycentric vertical axis of its plan profile.
Means as claimed in claim 8, characterised in that said linkage system comprises two axially slidable rods carried by the longitudinal members of the carriage, and connected at their rear ends to respective control devices and at their front ends to a grid-dragging rocker arm by way of respective connecting bars, the hinge pins between the rocker arms and connecting bars, and between the connecting bars and rods, being slidingly received within respective guide slots provided in the carriage.
Means as claimed in claim 8, characterised in that said linkage system comprises two axially slidable longitudinal rods which are connected at their rear end to respective control devices, and are provided at their front end with respective sliders carried by longitudinal members of the carriage, said sliders being provided with respective slots to which the ends of a grid dragging rocker arm are slidingly coupled, the sidepieces of this latter presenting respective profiled shoes which engage said rods such that they roll on these latter.
Means as claimed in claims 9 and 10, characterised in that said control devices are linear actuators.
Means as claimed in claim 7, characterised in that the members defining the lattice of said grid consist of a plurality of baffles of sinuous pattern in plan view, of which a fraction connects together two opposing sides of the peripheral frame of the grid, another fraction connects together two consecutive sides of the said frame, and a further fraction connects together pairs of adjacent baffles.
Means as claimed in claim 7, characterised in that said at least one constituent element consists of one of said baffles, said one baffle being elastically deformable, and at least one end of said one baffle being connected to the frame of the grid by an arm of variable length.
Means as claimed in claim 13, characterised in that said arm of variable length consists of a cylinder-piston unit.
Means as claimed in claim 7, characterised by comprising a processor integrated into the loading cycle central control unit, to which said regulating means for said at least one element of the grid are operationally connected.
Means as claimed in claim 15, characterised in that said processor comprises an operational unit arranged to control said regulating means cycle by cycle in accordance with a procedure comprising a random sequence of commands.
Means as claimed in claim 16, characterised in that said processor comprises two command activation units, these also being connectable and disconnectable in random manner, and of which one emits coarse adjustment signals and the other emits fine adjustment signals.
Means as claimed in claim 15, characterised by comprising a data entry unit, such as a keyboard, which is under the control of the operator and is connected to said processor.
Means as claimed in claim 15, characterised in that said processor comprises a unit operationally connected to the constituent devices of the system for supplying powders to said at least one hopper.
Ceramic tiles obtained by the method of claims 1 to 7 and by the means of claims 8 to 19.