EP2163366A1

EP2163366A1 - A method for obtaining cavities on surfaces of ceramic items and an apparatus for making ceramic items having at least one surface provided with cavities

Info

Publication number: EP2163366A1
Application number: EP09011724A
Authority: EP
Inventors: Tarozzi Fausto
Original assignee: Siti B&T Group SpA
Current assignee: Siti B&T Group SpA
Priority date: 2008-09-15
Filing date: 2009-09-14
Publication date: 2010-03-17
Also published as: IT1393379B1; CN101708627A; ITMO20080233A1

Abstract

The method for obtaining cavities (9) in surfaces (2A) of ceramic items (2), according to predetermined directions and patterns, involves the creation of cavities (9) in said surfaces (2A) of said ceramic items (2) in a high-cohesion green state.

Description

FIELD OF THE INVENTION

The invention relates to a method for obtaining cavities on surfaces of ceramic items and an apparatus for making ceramic items having at least one surface provided with cavities, particularly adapted for forming cavities of desired shapes and sizes in ceramic items such as tiles, slabs and the like.

BACKGROUND OF THE INVENTION

In certain special applications, the laying faces of ceramic items, such as tiles, slabs and the like are required to have cavities, formed in special patterns and arrangements.
This requirement arises, for instance, when the ceramic tiles or plates are used to form ventilated walls, i.e. walls covering façades of buildings, that are maintained at a predetermined distances therefrom to allow circulation of air flows in the gap defined therebetween.
These ventilated walls are mainly used for two purposes: a first purpose is to make a facing that creates a thermal barrier to protect the building from outside temperature changes, so that it can be maintained at an inside temperature that is substantially constant, or at least varying in a range of a few degrees; a second purpose is of aesthetic type, and consists in imparting a new, more architecturally attractive aspect to a faced building.
These ventilated walls consist of a trestle composed of upright and cross members that are joined together and form a bearing framing for the slabs that form the facing walls.
Such framing is designed to be attached to the front of the building and then, the facing tiles or slabs are secured thereto by special fasteners, in vertical or substantially vertical overlapped or side-by-side arrangements, typically row-column arrangements.
The tile fasteners have such a shape as to engage corresponding cavities that are formed in a particular pattern in the laying faces of the tiles or slabs, the term laying faces being intended to indicate the surfaces opposite to the exposed surfaces.
In prior art, these cavities are manually formed in fully finished tiles by one or more operators using milling cutters.
This prior art suffers from certain drawbacks.
A first drawback is that manual milling is a substantially long, troublesome and difficult process, due to the mechanical resistance of the finished tiles or slabs, which have already undergone a baking process.
This method of forming the cavities causes a considerable increase of ventilated wall manufacturing costs, as a large amount thereof, four on average, have to be formed for each tile or slab.
A second drawback is that the milling cutters are exposed to rapid deterioration, once more due to the mechanical resistance of finished tiles and slabs, and require frequent replacement.
A further drawback is that the manual cavities forming process is very slow and inaccurate and requires long times, eventually extending the overall ventilated wall preparation and assembly times.

OBJECTS OF THE INVENTION

One object of the invention is to improve the state of the art.
Another object of the invention is to provide a method for obtaining cavities on surfaces of ceramic items and an apparatus for making ceramic items having at least one surface provided with cavities, that allow cavities to be formed in predetermined patterns and arrangements in the laying surfaces of tiles or slabs, by an automatic process.
A further object of the invention is to avoid frequent replacement of cavities forming tools, particularly milling cutters.
Yet another object of the invention is to considerably speed up the process of obtaining cavities in the back of tiles and slabs.
A further object is to obtain identical and flawless cavities.
According to one aspect of the invention it is provided a method of making cavities (9) in surfaces (2A) of ceramic items (2), in predetermined directions and patterns, characterized in that said formation creation of cavities (9) in said surfaces (2A) of said ceramic products (2) in a high-cohesion green state. According to another aspect, the invention provides an apparatus for making ceramic items (2) having at least one surface (2A) with cavities, characterized in that it comprises: means for making said ceramic items (2) and said surfaces (2A) in a high-cohesion green state, to obtain finished ceramic items (2) and surfaces (2A); means for creating cavities (9) in said finished surfaces (2A) in predetermined patterns and directions.
Therefore, the method and apparatus for making cavities in surfaces of ceramic items afford automatic and quick formation of cavities, typically in laying faces of tiles and slabs, in the desired amounts and patterns, while causing little stress on the forming tools, such as the milling cutters, and providing a faster and more accurate and inexpensive processing method.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will appear more clearly upon reading of the detailed description of a method for obtaining cavities in faces of ceramic items and an apparatus for making ceramic items having at least one surface with cavities, as shown by way of illustration and without limitation in the accompanying drawings, in which:

Figure 1 is a highly schematic view of a segment of a line for manufacturing ceramic items, namely tiles, incorporating an apparatus for making cavities in laying faces thereof;
Figure 2 is a broken bottom schematic view of a step of making a cavity in a laying face of a ceramic tile according to the invention.

EMBODIMENTS OF THE INVENTION

Referring to the figures, numeral 1 designates a drier for ceramic items, such as tiles 2 and numeral 3 designates a kiln for firing tiles 2.
A conveyor line 4, typically having parallel belts 5, is provided between the drier 1 and the kiln 3, with tiles 2 being carried thereon from the drier, to be fired in the kiln 3 for final stabilization.
The conveyor line 4 incorporates a removal apparatus 6 which is mounted below the parallel belts 5 and has an abrasive wheel 7 mounted to a lifting or lowering unit, generally designated by numeral 8 which moves between a work position in which it removes ceramic material, and a rest position.
An enameling or decorating apparatus, schematically designated by numeral 14 may be also mounted between the drier 1 and the kiln 3, downstream from the removal apparatus 6.
A wheel 6A of the removal apparatus 6, or another element known to the skilled person, designed to form cavities in a solid body as it is lifted by the lifting unit 8 towards the lying faces 2A of the tiles 2, hollows out their surfaces, thereby creating cavities 9 of predetermined depth and size, as the conveyor line 4 moves, and in response to the movements of the lifting unit 8.
Furthermore, since the tiles 2 would be vertically lifted from the conveyor line during this hollowing step, due to the upward thrust of the wheel 6, to a position above the conveyor line 4, a pressure element 10 is provided to hold the tiles 2 pressed on the conveyor line 4 during formation of the cavities 9.
This pressure element comprises, for instance, a closed-loop belt 11 running on return pulleys, at least one of which is driven by a motor, for the belt 11 to run in synchronism with the conveyor line 4, and to form a segment 13 substantially parallel to the conveyor line 4 and designed to be held in contact with the tiles 2 as they run through the abrasive apparatus 6 during the hollowing step by means of a presser member 15.
In the method of making cavities 9 on surfaces of the lying faces 2A of ceramic tiles (2) (or slabs) the surfaces are hollowed out when the tiles 2, obtained by drawing a plastic mass of ceramic material or by a pressing step in a press die, come out of a drier 1 and are fully formed, in a green, dried and high-cohesion state, before being submitted to final firing.
In this state, the ceramic material that forms the tiles 2 has a high cohesion and compaction, but is inherently less resistant than it would be after firing, and can be thus easily hollowed out, which considerably enhances the abrasive action of the wheel 7.
The latter may be mounted to a lifting unit 8 which is required to be also capable of orienting it in tilted positions relative to the surfaces of the faces 2S of the tiles 2, to possibly obtain cavities having undercut profiles.
In one variant of the method for making cavities 9 in surfaces 2A of ceramic items 2, the cavities 9 may be also formed directly during forming of the ceramic items.
In this case, if the tiles 2 are obtained using a press that compacts ceramic powder material, the dies or punch of the press will have suitable reliefs that will impress their shape into the mass of ceramic material in the mold, thereby creating the cavities 9.
Conversely, if the tiles 2 are obtained by extrusion of ceramic material at a high-cohesion plastic state by a known extruder apparatus, the cavities 9 may be directly formed in the layer of extruded ceramic material, by providing movable punches at the exit of or within the forming line, for either alternately or continuously punching into the ceramic material.

Claims

A method for obtaining cavities (9) in surfaces (2A) of ceramic items (2), in predetermined directions and patterns, characterized in that said making involves the creation of cavities (9) in said surfaces (2A) of said ceramic products (2) in a high-cohesion green state.
A method as claimed in claim 1, wherein such creation comprises the removal of portions of high-cohesion green ceramic material from said surfaces (2A) using removal means (6, 7, 8).
A method as claimed in claim 2, wherein said removal occurs after drying and before firing of said ceramic items (2).
A method as claimed in claim 1, wherein said creation involves the making of said cavities (9) during formation of said ceramic items (2) in said high-cohesion green state.
A method as claimed in claims 1 and 4, wherein said formation involves the pressing of ceramic materials in a press die having reliefs for shaping said cavities (9) in said surfaces (2A).
A method as claimed in claims 1 and 4, wherein said creation involves the hollowing of said surfaces (2) by hollowing means (6, 7, 8) during extrusion of said ceramic items (2) in said high-cohesion green state.
An apparatus for making ceramic items (2) having at least one surface (2A) with cavities, characterized in that it comprises:
- means for making said ceramic items (2) and said surfaces (2A) in a high-cohesion green state, to obtain finished ceramic items (2) and surfaces (2A);

- means for creating cavities (9) in said finished surfaces (2A) in predetermined patterns and directions.
An apparatus as claimed in claim 8, wherein said creation means are selected between shaping means and removal means.
An apparatus as claimed in claim 8, wherein said creation means are selected between press-forming means and extrusion-forming means.
An apparatus as claimed in claim 8, wherein said removal means include hollowing means for removing ceramic material from said surfaces (2A), which are arranged in said predetermined direction.
An apparatus as claimed in claim 10, wherein said hollowing means include at least one milling unit (7) driven by drive means (9) alternating between a removal work position and a rest position.
An apparatus as claimed in claim 9, wherein said press-forming means include press dies having reliefs for shaping said cavities (9).
An apparatus as claimed in claims 7 and 10, wherein said making means further comprise a conveyor line (4) which is equipped with an opposing element (10) coinciding with said hollowing means (6, 7, 8), which acts against said ceramic items (2) during a work step of said hollowing means (6, 7, 8) on the side opposite to said hollowing means (6, 7, 8).