WO2011148338A1

WO2011148338A1 - Process and system for the formation of sheets of tesserae of mosaic

Info

Publication number: WO2011148338A1
Application number: PCT/IB2011/052302
Authority: WO
Inventors: Enrique Casalta
Original assignee: Proxima Technology S.L.
Priority date: 2010-05-26
Filing date: 2011-05-26
Publication date: 2011-12-01
Also published as: EP2576241A1; EP2390110A1

Abstract

Process for the formation of sheets of mosaic tesserae (F) wherein the joining step of each group of mosaic tesserae arranged chequered provides for the application - from the top - of the adhesive agent on an anti-adhesive substrate (6; 10) and the positioning of the group of tesserae on the adhesive agent applied to the anti-adhesive substrate (6; 10) maintaining the front faces of the tesserae facing upwards, so as to adhere the adhesive agent to the back faces of the tesserae. The adhesive agent is injected - from the top - on the anti-adhesive substrate (6; 10) according to linear bridges (15) for the connection of the sides of the adjacent mosaic tesserae (F).

Description

"Process and system for the formation of sheets tesserae of mosaic"

Field of the invention

The present invention refers to the formation of sheets of mosaic tesserae intended to be laid for the decorative coating of wall structures, floors and the like .

Sheets thus made have usually have standardized dimensions and the number of the tesserae of each sheet, arranged chequered, is evidently correlated to the dimensions thereof. For example, with squared tesserae having a side measuring 2 cm per sheet, also squared, may typically include 15 rows by 15 columns of tesserae .

State of the art

Mechanized systems for implementing entirely mechanical processes, which initially provide for a step of positioning single mosaic tesserae, typically quadrangular-shaped, within special container trays or "masks" are currently used for the formation of sheets of mosaic tesserae of the aforementioned type, made manually in the past. The mosaic tesserae, arranged chequered according to rows and columns and disjoined with respect to each other, are thus each connected with the adjacent tesserae by means of an adhesive, usually plastisols that can be heat polymerized, applied so as to form dots at the adjacent vertices of the tesserae.

In a first known process, the mosaic tesserae are initially positioned within container trays with the respective front decoration faces, i.e. the faces which in the laid condition of the sheets shall be arranged exposed, facing upwards for so as to visually verify wholeness thereof. Subsequently, the groups of mosaic tesserae thus composed are overturned so as to position the base or back faces of the tesserae upwards. The joining adhesive is thus applied - from the top - on the back faces of the tesserae, usually through a mechanized dispenser. Lastly, a flexible cover sheet made of anti-adhesive material, typically silicone sheet, is applied on the adhesive.

Upon exit from the gluing station, the sheets of mosaic tesserae are picked up by respective container trays and then transferred into packaging boxes.

This method, which - as mentioned - provides for the application of the adhesive directly on the back faces of the tesserae, reveals the drawback related to the impossibility to inspect and check the wholeness and the quality of the front faces of the tesserae after they have been overturned in the respective container trays. Should even only one of the tesserae be damaged following laying on the container tray, at the end of the gluing step, the entire sheet must be necessarily discarded.

Furthermore the adhesive applied - from the top - in the fluid state on the back faces of the tesserae may penetrate into the intersection area between adjacent tesserae and, particularly in the case of tesserae of low thickness, it may be visible on the front faces thereof with evident aesthetic drawbacks.

A further drawback of this method lies in the difficulty of managing and controlling the thickness of the adhesive applied - from the top - and in particular the height homogeneity.

Regardless of the use of pressing and levelling rollers at the end of the application thereof, sections of adhesive agents having different contact times with the atmosphere will have different hardening times before being subjected to the action of the rollers, with ensuing non-uniformity.

With the aim of attempting to at least partly overcome these drawbacks there was proposed a second method, which also provides for the initial insertion of the tesserae within container trays with the relative front faces facing upwards. Each container tray containing the tesserae can thus be inspected visually to verify the wholeness of the relative front faces, and thus it is overturned so as to arrange the tesserae within a second container tray so as to position the back faces upwards. Then there follows the gluing operating, which provides for the provision of a paper sheet made anti-adhesive and cut to size and the positioning thereof above a dispenser device provided with nozzles for supplying the adhesive from the bottom upwards against the lower face of the paper sheet, also in this case at dots corresponding to the adjacent vertices of the tesserae. At the end of the application of the adhesive, the paper sheet is deposited against the back faces of the mosaic tesserae positioned on the underlying container tray, therefore providing the mutual joining thereof. The sheet is thus pressed with a constant pressure against the back faces of the tesserae so as to as to obtain a homogeneous thickness of the applied adhesive.

Also this second method reveals serious drawbacks. Firstly, it also requires overturning the groups of tesserae before the step of application of the adhesive, with the need for providing special resources dedicate to such operation and with the risk of damaging the front faces.

Secondly, it does not allow providing an efficient visual inspection of the correct depositing of the adhesive, at the correct amount and positions, on the lower face of the paper sheet.

Furthermore, given that - as mentioned - the production of the adhesive by the dispenser occurs from the bottom upwards, the relative nozzles are subjected to obstruction by the adhesive with ensuing need for frequently stopping the machine for cleaning and maintenance thereof. Hence, the productivity of the of the systems operating with this second method is considerably limited.

A further drawback of this type of process lies in the impossibility of visually ensuring that all the mosaic tesserae correctly adhere to the paper sheet with the adhesive as well as, also in this case, that the front faces of the tesserae are maintained whole at the end of the gluing step.

In order to overcome these drawbacks it was proposed - in document EP-1722897A1 to avoid the operations of overturning the mosaic tesserae before the gluing step. In this case, the step of joining the tesserae provides for the application - from the top - of the adhesive agent on an anti-adhesive substrate and the positioning of the group of tesserae on the adhesive agent applied on said anti-adhesive substrate maintaining the front faces of the tesserae facing upwards, so as to adhere the adhesive agent to the back faces of the tesserae.

However, also this solution reveals drawbacks. Firstly, the adhesive agent is applied on the anti-adhesive substrate by means of a device for depositing drops having a support from which there projects a plurality of appendages which are embedded in a container tray for the adhesive agent and thus brought to contact with the substrate. This implies uneven application of the adhesive agent, risks of dirtying the line during the movements of the support with the embedded appendages, as well as problems related to the overall dimension and maintenance of the depositing device in its entirety.

The adhesive agent must be sufficiently fluid so as to be picked up by the support appendages and transferred to the anti-adhesive substrate, thus also in this case it consists in a plastisol that can be heat polymerised following the positioning of the tesserae on the anti-adhesive substrate, hence requiring the use of a heating oven along the line. Plastisol is poorly compatible with the concrete commonly used for laying the mosaic sheets on site, hence implying problems even from this point of view.

Lastly, this system is not practically useable in cases in which the tesserae are very small in size.

Summary of the invention

The object of the present invention is to overcome such drawbacks and this object is attained due to a process and a system generally defined respectively in claim 1 and in claim 7.

According to a preferred embodiment of the invention the anti-adhesive substrate is constituted by a regenerable endless belt.

Alternatively, the anti-adhesive substrate can be constituted by a discrete flexible plate.

The invention allows eliminating any need for overturning the tesserae, which are constantly maintained with the relative front faces facing upwards so as to allow a continuous visual control of the quality thereof. Also the correct application of the adhesive on the anti-adhesive substrate can be efficiently visually controlled, and the production of the adhesive - from the top downwards - avoids or at least drastically reduces the need for performing cleaning and maintenance operations on the dispenser device .

The distinctive methods of application of the adhesive advantageously allow obtaining a more efficient connection between the tesserae and a better stability of the relative sheets, also in cases in which the latter are very small in size (even measuring 2 cm or less per side) .

These effects, alongside a higher production speed and the possibility of using one-component polyurethane adhesives which do not require heat polymerisation, allow the process according to the invention and the system for the provision thereof to considerably increase the productivity, even up to 80%, with respect to the methods used currently, simultaneously considerably reducing the use of human resources dedicated to the implementation thereof.

Brief description of the drawings

Now, the invention will be described in detail with reference to the attached drawings, provided purely by way of non-limiting example, wherein:

-figure 1 is a schematic top plan view of the lay^¬ out of a system for implementing the process according to the invention,

-figure 2 is an enlarged view of a detail of figure 1, and

-figure 3 is a perspective view exemplifying a method for joining the mosaic tesserae implemented according to the invention.

Detailed description of the invention

With reference to figure 1, the process for the formation of sheets of mosaic tesserae according to the invention is implemented through a system essentially constituted by the components listed hereinafter:

- at least one line 1, constituted by a motor- driven endless belt, for supplying container trays or loading masks 2 within each of which there is introduced a plurality of quadrangular-shaped mosaic tesserae F arranged chequered in rows and columns. The mosaic tesserae F, disjoined with respect to each other, usually have a front decoration face, intended - in the laid condition - to be arranged exposed, and a back face or base opposite to the front face. According to a first aspect of the invention the groups of tesserae F are arranged, manually or more conveniently in a mechanized manner, within the respective container trays 2 with the respective front faces facing upwards, and they are thus maintained with such orientation for the entire cycle;

a gluing device constituted by a robot 3 arranged beside the line 1 and provided with a device 4 for dispensing fluid adhesive, typically of the one- component polyurethane type, supplied to the robot 3 by units 5 for melting the adhesive. The dispenser 4 will be described in detail hereinafter;

- an endless belt 6 arranged beside the supply line 1 on the opposite side of the robot 3 and defining a regenerable anti-adhesive substrate moveable endlessly, through a motorised group (not illustrated) , along the forward movement direction indicated by the arrow H. At one end of the belt 6 there can be possibly associated a supply line 7 provided for successively depositing - on the surface of the belt 6 - discrete sheets 10, i.e. cut to size, of a flexible material such as for example silicone paper, plastic and the like, adapted to constitute anti-adhesive substrates alternatively to the surface of the belt 6;

- a manipulator robot 8 arranged beside the belt 6, on the opposite side with respect to the supply line 1, and provided in a per se known manner, through a suction unit 9, for collecting - from time to time - the groups of tesserae F contained in the loading container trays 2 arriving along the supply line 1 and depositing each group of tesserae on the anti-adhesive substrate constituted by the regenerable endless belt 6 or, alternatively, by the sheets 10 deposited thereon;

- a packaging line 11 on which there are loaded boxes 12 coming from a warehouse 13 and within which the sheets of mosaic tesserae F, formed from time to time through the methods described hereinafter, are transferred by the belt 6 through the manipulator robot 8.

The system is also provided with a series visual inspection stations, not illustrated in detail in that known to a man skilled in the art, typically constituted by cameras operatively connected to a pre^¬ programmed system for managing images to compare the detected images with reference images and verify congruity thereof. The cameras will be positioned so as to record the groups of mosaic tesserae F positioned from time to time in the respective container trays 2 advancing on the supply line 1, the area for applying the adhesive on the anti-adhesive substrate constituted - as mentioned - by the belt 6 or alternatively by the sheets 10 positioned thereon from time to time as well as the sheets F subsequently transferred to the packaging line 11.

Now, with more detailed reference to figure 2, the dispenser 4 of the adhesive comprises a series of injectors 14 directed orthogonally to the forward movement direction H of the anti-adhesive substrate 6 (or 10) and moveable, synchronously with the movement thereof, alternatingly orthogonally and parallel to the forward movement direction H for providing on the anti- adhesive substrate 6 (or 10) linear bridges 15 for the interconnection of the sides of the adjacent tesserae F .

The linear bridges 15 will be oriented orthogonally to the sides of the tesserae F and, in the case of the illustrated example, they correspond to the centerlines of the sides of the adjacent mosaic tesserae F of each group. Such arrangement could however be different, and two or more linear bridges per side could be provided for.

As mentioned, the mosaic tesserae F are arranged chequered in rows and columns, of which the first are orientate orthogonally and the second parallel to the forward movement direction H: the number of injectors 14, arranged parallel to the rows of tesserae F, is greater than at least one unit with respect to the tesserae F of such rows. I.e., in the typical case in which each group comprises fifteen rows and fifteen columns of tesserae F, the injectors 14 are normally sixteen .

The process of formation of the sheets of mosaic tesserae F implemented by the system thus described is as follows.

In the loading step, the mosaic tesserae are - as mentioned - positioned in the respective container trays 2 arranged chequered, with the relative front faces facing upwards. Then, while the container trays 2 are transferred from the supply line 1 towards the zone for picking up the tesserae by the manipulator robot 8, the relative front faces are inspected by the camera vision system so as to verify not only the correct positioning but also the absence of surface faults or flaws .

At the same time, and synchronously with the forward movement of the supply line 1, the gluing robot 3 proceeds to the application of the adhesive fluid on the anti-adhesive substrate constituted by the surface of the regenerable belt 6 or, alternatively, by the sheets 10 deposited thereon from time to time. The dispenser 4 is moved, synchronously with the movement of the anti-adhesive substrate 6 (or 10), by alternating motion orthogonally and parallel to the forward movement direction H while the injectors 14, controlled electronically, inject the adhesive on the anti-adhesive substrate 6 (or 10) - from the top downwards - according to the paths defining the linear bridges 15 mentioned previously, for example corresponding and orthogonal to the centrelines of the sides of the adjacent mosaic tesserae F of each group arranged within the relative container tray 2. Such arrangement is exemplified in figure 3, in which fictitiously the mosaic tesserae F joined to the bridges 15 are illustrated at an overturned position.

Following each cycle of application of the adhesive implemented by the dispenser 4 the manipulator robot 8 picks up, through the respective suction device 9, each group of mosaic tesserae F from the respective container tray 2 on the supply line 1 and transfers it above the adhesive grid 15 previously applied on the anti-adhesive substrate 6 or 10. The group of tesserae F is thus deposited, in the same configuration in which it was picked up i.e. with the front faces of the tesserae facing upwards, on the adhesive grid 15, thus obtaining the joining thereof with the relative back faces .

After a relatively brief period of time, sufficient to guarantee the stability of the adhesive against the back faces of the tesserae and the ensuing mutual joining thereof, each sheet of tesserae F thus formed is picked up from the belt 6 by the same manipulator robot 8 and thus transferred to the packaging line 11 for packaging. The information provided above clearly shows that during the entire process of formation of the sheets, the mosaic tesserae F remain constantly oriented with the relative front decoration faces facing upwards. This allows the visual inspection system to constantly control, besides the presence and the correct positioning of the tesserae, also the wholeness and the absence of surface flaws of such front faces, alongside the correct production of the adhesive applied from time to time on the anti-adhesive substrate.

Obviously at the end of the formation cycle, each sheet of tesserae F will be constituted solely by the tesserae and by the adhesive grid 15 which joins the back faces thereof, in the case in which the anti- adhesive substrate is constituted by the surface of the regenerable belt 6, or it will also include the sheet 10 in the alternative case in which the latter is used for constructing the anti-adhesive substrate. In the first case, the auxiliary anti-adhesive sheet may then be inserted, with separation function, between each sheet F introduced from time to time in the box 12 along the packaging line 11 and the underlying sheet F.

The advantages deriving from the process according to the invention lie, besides the elimination of the need of overturning the mosaic tesserae and the relative drawbacks mentioned at the beginning, in the possibility of a constant visual inspection of the quality of the sheets of tesserae F, in considerable reduction of the need for performing maintenance and cleaning operations on the adhesive dispenser and, lastly, in a noticeable increase of productivity.

Furthermore, the distinctive methods of application of the adhesive allow both using adhesives that do not require heat polymerization and which are compatible with the materials laying the mosaic tesserae F on site and obtaining a more efficient connection between the tesserae and an improved stability of the relative sheets, also in cases where the tesserae are very small in size.

Obviously, the construction details and the embodiments of the system for implementing the process may widely vary with respect to what has been described and illustrated, without departing from the scope of protection of the present invention as defined by the claims that follow.

Claims

1. Process for the formation of sheets of mosaic tesserae (F) comprising the steps of providing groups of mosaic tesserae disjoined and arranged chequered, wherein the tesserae of each group are quadrangular- shaped and have a front decoration face and a back joining face, and joining the back face of each mosaic tesserae of each group with the adjacent tesserae by means of an adhesive agent for forming a sheet of mosaic tesserae (F) , wherein the joining step provides for the application - from the top - of the adhesive agent on an anti-adhesive substrate (6; 10) and the positioning of the group of tesserae on the adhesive agent applied on said anti-adhesive substrate (6; 10) maintaining the front faces of the tesserae facing upwards, so as to adhere the adhesive agent to the back faces of the tesserae, characterised in that the adhesive agent is injected on said anti-adhesive substrate (6; 10) according to linear bridges (15) for interconnecting the sides of the adjacent mosaic tesserae (F) .

2. Process according to claim 1, characterised in that the anti-adhesive substrate (6; 10) endlessly moves along a forward movement direction and the adhesive agent is injected synchronously with the movement of said anti-adhesive substrate (6; 10) .

3. Process according to claim 1 or 2, characterised in that the anti-adhesive substrate is constituted by a regenerable endless belt (6) .

4. Process according to claim 1 or 2, characterised in that the anti-adhesive substrate is constituted by a discrete flexible plate (10).

5. Process according to any one of the preceding claims, characterised in that it further includes the visual inspection of the front faces of the tesserae and of the adhesive applied on said anti-adhesive substrate (6; 10) .

6. Process according to any one of the preceding claims, characterised in that said linear bridges (15) correspond to the centrelines of the sides of the adjacent mosaic tesserae (F) .

7. System for the formation of sheets of mosaic tesserae (F) including means (1, 2) for supplying groups of quadrangular-shaped mosaic tesserae disjoined and arranged chequered with the tesserae of each group constantly arranged with respective front decoration faces facing upwards and respective back joining faces facing downwards, means (3, 4) for applying - from above - an adhesive on an anti-adhesive substrate (6; 10), means (8, 9) for transferring each group of mosaic tesserae on the adhesive applied on said anti-adhesive substrate (6; 10) for adhering such adhesive to the back faces of the tesserae joining each tesserae with the adjacent tesserae so as to form the sheet of mosaic tesserae (F) , and means (8, 9) for transferring the sheets of mosaic tesserae (F) thus formed to a packaging line (11), characterised in that said means for applying the adhesive include a dispenser (4) designed to inject the adhesive agent onto said anti- adhesive substrate (6; 10) according to linear bridges (15) for interconnecting the sides of the adjacent mosaic tesserae (F) .

8. System according to claim 7, characterised in that the anti-adhesive substrate (6; 10) endlessly moves along a forward movement direction (H) and said dispenser includes a series of injectors (14) directed orthogonally to said forward movement direction and moveable alternating, synchronously with the movement of said anti-adhesive substrate (6; 10), orthogonally and parallel to said forward movement direction (H) for providing said linear bridges (15) .

9. System according to claim 7 or 8, characterised in that the anti-adhesive substrate is constituted by a regenerable endless belt (6).

10. System according to claim 7 or 8, characterised in that the anti-adhesive substrate is constituted by a discrete plate (10) .

11. System according to any one of claims 8 to 10, wherein the mosaic tesserae (F) of each group are arranged in rows and columns respectively orthogonal and parallel to said forward movement direction (H) , characterised in that the injectors (14) of said series are at least one more than the number of mosaic tesserae (F) of each row.