CN1298521C - Method and device for mfg. tile and ceramic board, and tile and ceramic board mfg. thereby - Google Patents

Abstract

A method for manufacturing construction elements such as ceramic tiles and slabs, consisting of pressing in one or two stages a mass consisting of at least two ceramic materials generally in powder form at least partially mixed together and having different properties, generally different colours, followed by firing of the pressed product, characterised by comprising the following operative steps: separately preparing bodies of generally irregular form starting from at least one ceramic material generally in powder form having properties different from those of said at least two materials of said mass; adding said bodies to said mass before the final pressing; and subjecting the product to a surface finishing operation before or after said firing step.

Description

Method and apparatus for manufacturing ceramic tiles and tiles

technical field

The present invention relates to the manufacture of ceramic building materials, generally ceramic tiles, but also of large dimensions equally suitable for such use, or of smaller dimensions and/or of substantially different One or more elements of a shape.

The invention also relates to a device for carrying out the method.

Background technique

It is well known that the tile manufacturing industry is constantly seeking new or reforming patterns in its decorative designs, with current emphasis on imitating the appearance of natural stones and rocks such as marble, a material known to have elongated veins or stripes of various shapes and colors .

Imitation of decorative design patterns that symbolize natural stones or rocks, such as marble or granite, which are typical aesthetic elements, can be obtained through modern ceramic manufacturing techniques that use porcelain stone materials as a typical example, which is well known to those skilled in the art and will not be repeated here .

In general terms, such decorative design patterns relate to the entire aggregate material of the tile or slab, eg the entire thickness, or only to the exposed surface of said tile or slab.

Especially in the second case, a double charge is used, the first charge uses a matrix material of no special value for forming the support layer of the tile, while the second charge uses a facing material with characteristics, which can be applied on the tile or The exposed face of the porcelain plate provides the expected features.

The second material may comprise at least two generally powdery ceramic materials at least partially mixed together, having different properties, generally different colours.

Document WO-A-9615888 discloses a method and associated equipment for compacting powders for the manufacture of pressed tiles. The method comprises the operations of: forming a powder layer on a conveying device that conveys the powder layer to a mould; isolating a portion of said layer inside a mold frame of said mold by bringing said mold frame close to said conveying device; And the portion of the layer isolated by the formwork is compacted with the punches of the die descending within the formwork.

The apparatus for carrying out the above-mentioned method comprises conveying means for conveying the powder layer to a die, said die comprising a punch and a die carrier, wherein the punch is movable in a direction substantially perpendicular to said layer, the punch connected to associated beams for compacting the powder; independent of said punches and movable in a direction substantially perpendicular to said layer, said die frames are slidably engaged inwardly with said punches, and are provided with as isolating means to isolate a portion of said layer on said conveying means.

According to the foregoing, natural stones or rocks, such as marble, are generally characterized by stretched veins and striations of various forms and colours, generally resulting from the agglomeration of agglomerates of natural different types of constituents with irregular aggregation and dispersion , rather irregular.

The natural stone or rock, such as marble, presents a further stage characteristic of having different types of inclusions, nodules, agglomerates, etc., which are very different from the matrix matrix of the stone or rock at least in terms of color.

As is known to those skilled in the art, materials often originate, for example, from recrystallization processes of natural components, such as calcite, aragonite in limestone or dolomite.

These inclusions vary greatly in size and morphology. Usually in elongated form, the cross-section of which generally exhibits a band around the edge, usually of generally irregular width, usually with various shaded undertones and one or more colorings, usually all distinct from the main part the difference.

Contents of the invention

The main object of the present invention is to provide a device that can be used for the manufacture of ceramic building materials, generally ceramic tiles and porcelain slabs, having the aforementioned multiple colors typical of the appearance of natural stones such as marble or rocks, in particular decorated with various colors and Shaped textures and striations, also having regions of generally irregular shape surrounded by lines having a different appearance than the entire surrounding matrix, and may be at least partially surrounded by bands or halos of irregular width, the The stripes or halos generally have at least one color that differs in part from the inside or outside of the area.

Said areas, also referred to as spots, essentially constitute inclusions, concretions or agglomerates representing the aforementioned natural stones or rocks such as marble.

According to one aspect of the present invention there is provided a method of manufacturing ceramic tiles and porcelain slabs, said method comprising: one-stage or two-stage pressing of an aggregated material consisting of at least two powders, at least partially mixed together and have different colors of ceramic materials; then the pressed product is fired, which is characterized in that it includes the following operation steps: through at least one powdery material with different colors from the at least two materials of the aggregated material The ceramic material alone prepares irregular-form inserts which are added to the aggregate mass before the final pressing and finishing operations on the surface of the article before or after the firing step.

According to another aspect of the present invention, there is provided an apparatus for carrying out the above method, comprising: a one-stage or two-stage pressing station with corresponding devices for supplying ceramic starting materials; The roasting station of the product formed by the pressing station, the downstream of the pressing station or the roasting station is provided with a device for trimming the exposed surface of the product, it is characterized in that the supply device is connected to a production line , the production line is used to form inserts that are inserts of the products produced by this equipment.

In general, decorative ceramic articles are constructed from preformed correspondingly suitable inserts as inserts for the final product. According to the present invention, said inlay generally has an irregular shape and a relatively small size, by relatively small size I mean much smaller than the size of the tiles and tiles to be manufactured.

Said inserts generally comprise at least one ceramic material, generally in powder form ready for compaction, which is to be added to the ceramic material generally in powder form for the manufacture of china stones as explained in the preamble.

The at least one ceramic material, which is generally in the form of powder, has different characteristics, generally different colors, from the porcelain stone-like material.

According to an advantageous feature of the invention, the insert of said decorative article can be at least partially covered by at least one ceramic composition, generally a top glaze, which is generally compatible in characteristics such as color with the constituent materials of said insert and with the final product , such as ceramic tiles or porcelain plates, the carrier material is different.

The insert can have any shape and size.

Regarding its shape, it is generally irregular and preferably elongated. The outer surface of the elongated shape is generally preferably smooth, ie avoids having points or other protruding sharp edges where practical.

With regard to its dimensions, especially its transverse dimension, which is generally proportional to the usual thickness of the charge filled in the tile or porcelain slab mold, according to the test results obtained in the production of the experimental plant of the technology of the present invention, the embedding of the elongated shape It has proven expedient for the bodies to have an average transverse and longitudinal dimension of 5-15 mm and 10-50 mm, respectively, but this value is given only as an example.

Ceramic tiles or porcelain slabs, the carrier material of which incorporates said inserts, preferably only in its surface layer, is subjected to a surface finishing operation, generally a grinding operation, so as to expose its outer surface partially or integrally as described, the The exposed outer surface is one or more colors.

Said smoothing is preferably carried out immediately after forming by pressing. In addition, it can be performed after firing.

The features and advantages of the invention will be described in detail below with reference to the non-limitative examples shown in the drawings, in particular with regard to the example of the front of the apparatus for carrying out the method.

Description of drawings

Figure 1 is a side view of the present invention.

Figure 2 is a top view of the above figure.

Figure 3 is the III-III section shown in Figure 2, but on an enlarged scale.

FIG. 4 is a perspective view of the assembly shown in FIG. 3 .

Fig. 5 is a V-V section shown in Fig. 4 .

Figure 6 is a partial cross-sectional view of a charge charged into a mold cavity for making a ceramic tile or slab according to the invention.

Figure 7 is a cross-sectional view exactly similar to the previous figure showing a compacted tile or porcelain slab.

Figure 8 shows the same tile after it has been ground down.

Figure 9 is a top view of the above figure.

Figure 10 is a computer processed image of a type of marble decoration according to the present invention.

Detailed ways

Said drawings, in particular Figures 1 to 5, show the upstream part of the ceramic tile or porcelain slab manufacturing plant, the downstream part of the manufacturing plant shown for the sake of simplicity substantially successively comprises: a for starting material (starting material), to which the part shown in Figure 1 extends; a forming station, which may be of the single or double pressing type; possible grinding or polishing stations; a firing station, for example, with There are single or multi-layer carriages for moving the tiles; and a sanding or polishing station if it is not located downstream of the forming station.

The part of the apparatus shown in Figures 1 to 5 constitutes a production line for forming substantially irregular shaped decorative inserts (see Figures 6 to 10) for finished products such as tiles and porcelain slabs. The insert is generally of relatively small size and, preferably, is of elongated form, generally peanut-shaped as illustrated.

For example, said inlay 1 has an average transverse dimension and an average longitudinal dimension of 5-15 mm and 10-50 mm, respectively. In Figures 1 and 2, all said inserts 1 have the same shape and size for the sake of clarity.

The production line basically comprises a compacting station 2 , a cutting and trimming station 3 , a coating station 4 and a collecting and moving system 5 .

In particular, the compacting station 2 includes a motorized conveyor belt 20 , for example, driven by a gear motor with an integrated transmission, whose upstream end is located below a vertical distribution pipe 21 .

Connected to the discharge opening of said distribution pipe 21 is an adjustable valve member (not shown), which valve member is preferably controlled by a system for controlling the rotational speed of the conveyor belt 20 .

A set of conduits, three shown, discharges to said distributing pipe 21 and activates them on given command, for example in the presently discussed process, according to a stochastic relationship integrated with the control system of the entire plant (may vary by selection).

Each individual conduit 22 feeds the underlying distribution conduit 21 with at least one ceramic material, generally in the form of a powder mixed to varying degrees with the material(s) fed by the other conduits 22 .

For example, in the case where two materials are fed through the same pipe 22, the materials generally have different properties, such as different colors, and are completely or partially mixed to produce salt and pepper types (partial pearlite type) (salt and pepper) or a mix of texture/stripe types.

For example, the material fed through the individual conduits 22 may be aerosolized, ground or particulate powders obtained including ceramic demi-glazes or glaze mixtures and mixtures of these.

It should be noted that said material, substantially in powder form, has different characteristics, substantially different Color, to form ornaments of natural stone or rock type, such as marble, with veins or streaks as indicated at 10 in said figure.

The conveyor belt 20 is arranged in such a manner that it can be elastically deformed, the reason for which will be revealed later. For example, it may consist of a rubber conveyor belt with a suitable filling compound corresponding to elastic deformation and mechanical strength.

In the center of the outer section (outward branch) of the conveyor belt 20 there is a guide ring 23, where the conveyor belt is tubular along its relatively short length by folding up the longitudinal edges of the conveyor belt (Figs. 4 and 5). What is achieved is that, at a distance outside said ring 23, the longitudinal edges overlap, where the compacting device 24 is also arranged.

Basically, said ring 23 and said means 24 provide a generally funnel-shaped structure ( FIGS. 4 and 5 ), at its upstream and downstream ends, the outer section of conveyor belt 20 essentially exhibiting two progressive narrowing and widening respectively. groove shape (Figures 1 and 2).

The ring 23 is supported by a support portion 25 provided on the support structure of the conveyor belt 20 (Fig. 4), the inner surface of the ring 23 is shaped as a truncated cone, its small end is arranged in the downstream direction, and its circumference is smaller than that of the conveyor belt 20. width (see Figure 5).

Said ring 23 and said supporting portion 25 are also provided with corresponding respective notches above for inserting and removing the conveyor belt 20 ( FIGS. 4 and 5 ). In addition, it is also possible to divide the ring 23 into at least two parts which can be engaged with each other.

The compacting device 24 comprises a peripherally equidistant set of idler wheels 240, four in the illustrated example, arranged to roll along the tubular portion of the conveyor belt 20 leaving the loop 23 (Figs. 1-5). .

In particular, two wheels 240 are placed on a horizontal plane and the other two are arranged on a vertical plane, the two planes intersecting along the longitudinal axis of said ring 23, each wheel 240 being constantly elastically Pressed against the tubular portion of the conveyor belt 20, the thrust member is indicated by reference 241 in FIGS. 1 and 2 .

The pushing member 241 may be composed of a hydraulic or pneumatic cylinder-piston device, a flat helical or helical spring, a reed or equivalent components.

The outer shape of the wheel 240 in the figure is cylindrical, and other forms are not excluded, for example, a circumferential groove with a circular arc cross-section.

As an alternative to the wheel 240, a circumferentially encircling series of sliders with arcuate active surfaces or equivalent may be used.

Agglomerates 210 of loose ceramic material are applied without interruption on the upstream side of the conveyor belt 20 and are made into a continuous solid by a compacting device 24 from which a linear body emerges at the outlet of the conveyor belt 20 when previously overlapping When the two longitudinal sides of the body are opened, the linear body is naturally divided into agglomerates 11 of various shapes and sizes (Figs. 1 and 2).

It should be noted that said thread-like bodies are compacted with a specific pressure which is less than the pressure used for compacting the final tile or porcelain slab, approximately substantially half of the latter.

The agglomerates are conveyed to a chute 12 leading to the cutting and trimming station 3, between the downstream end of the conveyor belt 20 and said chute 12, an outflow channel is also provided for collecting and removing the size Agglomerated clumps that are too small.

Said conveyor belt 20 may also be arranged in combination with at least one further, identical conveyor belt for compacting loose starting material with different properties, usually at least different from the bulk material 210 compacted by conveyor belt 20 . color. In Fig. 2, said at least one further conveyor belt is schematically indicated by the dotted rectangular box marked 101 and may also lead to a chute 12, as indicated by arrow A, or discharge onto a collection and removal system , as indicated by arrow B.

The cutting and trimming station 3 comprises an inclined cylinder 30 with a non-horizontal axis, which is driven in rotation by a suitable drive 31 , such as a gear motor combined with a transmission.

The components contained inside the cylinder 30 (not shown for brevity) have two functions: one is to break up the agglomerate 11 into smaller inserts 1, for example having the shape and dimensions as previously described, and the other is to Sharp edge portions on the insert 1 after breaking the agglomerate 11 are smoothed. Said dual function components may include, for example, ribs, pins and/or similar components of different shapes and sizes.

In combination with said components, or instead, holes with sharp edges may be provided in the wall of the cylinder 30 . In Figures 1 and 2, the holes are equal diamonds, but this is purely an example.

Said cylinder 30 discharges to the coating station 4, and there is also a vertical distribution pipe 42 for the ceramic batch, which consists of at least one substantially powder Shaped, different characteristics from the loose starting material 210, at least a different colored material.

The formulation may comprise different kinds of powders or granules, for example, dusty, ground or particulate powders or chromophore oxides, or prepared from ceramics, semi-glazes or glaze mixtures, or mixtures thereof.

The coating station 4 comprises an inclined cylinder 40 with a non-horizontal axis, which is driven in rotation by a suitable drive means 41, such as a gear motor combined with a transmission.

The interior of the cylinder 40 is provided with means (not shown for the sake of simplicity) that facilitate the coating of the insert 1 with the formulation, said means may include ribs or protrusions of various shapes and sizes.

By adjusting the rotational speed of the cylinder 40, and/or opening the outlet valve of the steering tube 42, the thickness and extent of the coating covering the insert 1 can be selected simultaneously.

Basically, the following can be obtained: fully covered inlays (shown on the left side of Figures 6-9 and presented in the third block in the lower middle of Figure 10); partially covered inlays (located in Figure 6 -9 middle and bottom right in Figure 10); and completely uncovered inserts (right in Figures 6-9 and bottom left in Figure 10).

Uncoated inserts 1 can be made by temporarily closing the distribution tube 42 with or without keeping the cylinder 40 running, or by bypassing the cylinder 40 with a suitable deflection redirection device, and directing the product leaving the station 3 directly. It is obtained by transporting to the collection and removal system 5.

It should be noted that in some processes, such as the forming of large-scale porcelain slabs, it is possible to bypass the aforementioned cutting and trimming station 3 while removing or retaining the coating step.

In the example shown, the coating is carried out substantially dry, but other methods are not excluded. For example, the product leaving the cylinder 30 can be conveyed onto a mesh conveyor belt, sprayed or dripped with a suitable liquid glaze, and then dried before being sent to the collection system 5, or directly to the feeding device of the pressing station of the equipment .

As a variant, the mesh conveyor belt may pass through an enamel shower plate or a dip bath, at the exit of which a suitable fan may be provided.

There is no hindrance to combining the three used processes. For example, the processed insert 1 from station 4 may be followed by an operation such as spraying or dripping, so that the coating on the insert 1 includes a (full or partial) interior made of a first ceramic composition, such as a glaze. layer, and a (total or partial) outer layer consisting of a second ceramic composition, such as a glaze having characteristics different from the preceding glaze, typically a different colour.

Furthermore, downstream of the cylinder 30, at least one deflection guide can be provided to deflect at least a part of the arriving insert 1 to the position of coating (glazing), which can be carried out by spraying, dripping or dipping, if necessary.

Returning to Figures 1 and 2, it can be seen that the inserts 1 (coated or uncoated) leaving the cylinder 40 are collected by a system 5 comprising two mutually perpendicular moving conveyor belts 50 and 51 .

Between the cylinder 40 and the upstream conveyor belt 50, there is provided a chute 52 with an outflow (not visible in the figure) between it and said conveyor belt 50 for collecting and recirculating excess glaze powder.

The insert 1 obtained in this way is fed into the feeding system of the forming station of the device and can be used as described hereinafter.

In the case of single-stage forming, i.e. if the generally soft ceramic aggregate mass used for the manufacture of ceramic tiles or slabs is compacted to the desired degree by a single pressing in a single pressing device, the insert 1 can be yes:

- premixed with said generally soft ceramic aggregate mass if a single charge method is used,

- pre-mixed with the second layer of said aggregate material if the double charge method is used,

- No matter which charging method is used, it can also be placed directly on the soft aggregate material after charging.

The foregoing is equally valid for two-stage forming systems, ie if the generally soft ceramic aggregate mass used for the manufacture of ceramic tiles or slabs is compacted to the desired degree by two successive pressings in a double pressing device. In this case, the insert 1 can also be arranged on the product leaving the first pressing device, ie before the second or final pressing.

Said direct disposition to said soft aggregated material or product may be achieved by any suitable means, eg a distribution belt or a hopper with spreading means.

After pressing, the shaped tiles or slabs may be subjected to at least one surface finishing operation, generally smoothed or polished, followed by firing.

Alternatively, said grinding or polishing may be performed on the fired product.

By way of explanation, the insert 1 according to the invention can be used in general for the manufacture of porcelain stone types, in particular for tiles or porcelain slabs with a decorative effect of natural stone or rock such as marble, as shown in the example in FIG. 10 , but not Not limited to this.

In this respect, nothing prevents the use of the insert 1 for porcelain slabs or tiles having a more regular or consistent matrix than that shown in FIG. partially pearlitic type) from an initial ceramic mixture.

Claims (33)

1. A method of manufacturing ceramic tiles and porcelain slabs, said method comprising: one-stage or two-stage pressing of an aggregated mass consisting of at least two powdered ceramic materials at least partially mixed together and of different colours. Composition; Then the product after pressing is roasted, it is characterized in that, comprises the following operation steps: - a separate preparation of irregular-form inserts (1) by at least one powdery ceramic material having a different color from said at least two materials of said aggregate mass, - adding said insert (1) to said aggregate mass before the final pressing, and - performing finishing operations on the surface of the article before or after said firing step. 2. Method according to claim 1, characterized in that said insert is produced by cutting off a pre-compacted accumulation of said at least one material in powder form. 3. The method of claim 2 wherein said accumulation is compacted by a pressure less than that at which said article is finally formed. 4. A method according to claim 2, characterized in that, during or after said cutting-off step, said insert (1) is subjected to a finishing operation aimed at eliminating roughness such as sharp edges. 5. The method according to claim 2, characterized in that the insert (1) is subjected to at least one coating operation in order to coat it with at least one layer of at least A ceramic composition coats at least a portion of the outer surface of the insert. 6. The method as claimed in claim 5, characterized in that said at least one coating operation is performed by depositing an aggregate consisting of aggregates of said insert and powdery aggregates of said at least one ceramic ingredient mixed together. 7. A method as claimed in claim 5, characterized in that said at least one coating operation is carried out by spraying said insert with a suitable fluidized at least one ceramic composition. 8. Method according to claim 5, characterized in that said at least one coating operation is carried out by subjecting said insert (1) to a droplet distribution of said at least one ceramic composition in fluid form. 9. The method of claim 5, wherein said at least one coating operation is performed by passing said insert through a grid shower or bath of said at least one ceramic material in liquid form . 10. A method as claimed in claim 5, comprising at least two successive coating operations using ceramic formulations of different colours. 11. Method according to claim 1, characterized in that adding said inserts to said aggregate mass is produced by distributing said inserts (1) throughout said aggregate mass. 12. A method according to claim 1, characterized in that adding said inserts (1) to said aggregated mass is produced by distributing said inserts (1) in an upper layer of said aggregated mass. 13. Method according to claim 1, characterized in that adding said inserts (1) to said aggregate mass is produced by depositing said inserts (1) on the upper surface of said aggregate mass . 14. Method according to claim 1, characterized in that adding said inserts (1) to said aggregate mass is carried out before the second pressing stage by depositing said inserts (1) on a The first stage is achieved by corresponding compaction on the upper surface of the aggregated material. 15. The method of claim 1, wherein said finishing operation comprises smoothing. 16. An apparatus for implementing the method of claims 1 to 15, comprising: a one-stage or two-stage pressing station with respective means for supplying ceramic starting material; The roasting station of the formed product, the downstream of the pressing station or the roasting station is provided with a device (3, 4) for trimming the exposed surface of the product, characterized in that the supply device is connected to a Production lines (2, 3, 4) for forming inserts (1) as inserts for products produced by the plant. 17. Plant according to claim 16, characterized in that said production line comprises a moving conveyor belt (20), the outer section of which is adapted to receive loose aggregated material comprising at least one powder ceramic material in powder form having a different color from the starting material, the outer section of the conveyor belt is provided with a compaction system (23, 24) which enables the Aggregate material is solid. 18. Apparatus according to claim 17, characterized in that the conveyor belt (20) runs continuously via an adjustable drive. 19. Apparatus according to claim 17, characterized in that said conveyor belt (20) is elastically deformable. 20. Apparatus according to claim 19, characterized in that said compaction system comprises: an intermediate guide member (23) arranged so that a part of said moving outer section assumes a tubular shape; Downstream compacting means (24) pressed against the tubular portion of said conveyor belt (20). 21. The device according to claim 20, characterized in that said guide member (23) comprises a through hole penetrated by said outer section and made in the shape of a truncated cone, the The small end faces downstream and has a perimeter at least less than the width of the conveyor belt (20). 22. The apparatus according to claim 20, characterized in that said compacting device (24) comprises a set of surrounding compacting parts (240) with a certain contour shape, and the compacting parts are distributed on said conveyor belt (20 ) around the tubular portion, the compacting member is continuously kept pressed against the tubular portion by the action of the elastic thrusting device arranged behind it. 23. Apparatus according to claim 22, characterized in that said compacting elements (240) each comprise an idler wheel lying in a plane containing the axis of said frusto-conical channel. 24. Equipment according to claim 17, characterized in that a cutting station is provided downstream of said conveyor belt for obtaining said inserts (1) from said compacted aggregate and for smoothing said Rough sharp edges of the embedded body. 25. The device according to claim 24, characterized in that the cutting station (3) comprises a rotating inclined cylinder (30) on its inner surface provided with pins of different shapes and sizes and/or parts of the ribs. 26. Apparatus as claimed in claim 25, characterized in that at least a portion of said cylindrical wall is provided with sharp-edged holes. 27. The equipment according to claim 17, characterized in that at least one coating station (4) is arranged downstream of the conveyor belt (20) or the cutting station (3), for passing through a layer of at least one The insert is at least partially coated with a ceramic composition having a different color from at least one constituent material of the insert (1). 28. Apparatus according to claim 27, characterized in that said at least one coating station (4) comprises: an inclined rotatable cylinder (40) into which said inserts (1) flow; A distributor (42) for said at least one ceramic ingredient in powder form. 29. Apparatus according to claim 28, characterized in that the inner surface of the cylinder (40) is provided with mixing elements in the form of protrusions or ribs. 30. Apparatus according to claim 27, characterized in that said at least one coating station (4) comprises a support and transport device for said insert, at least one for said at least one A device for spraying ceramic ingredients is integrated with the support and conveying device. 31. The apparatus according to claim 27, characterized in that said at least one coating unit (40) comprises a support and transport device for said insert, at least one for said at least one ceramic The dosing device is integrated with the supporting and conveying device. 32. Apparatus according to claim 27, characterized in that said at least one coating unit (4) comprises a support and transport device for said insert, which is passed through said at least one At least one spray grid or immersion bath for the ceramic batch. 33. The apparatus of claim 16, wherein said finishing means includes at least one grinding or polishing mechanism.

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