AUTOMATIC MACHINE FOR THE APPLICATION OF ADHESIVE TO PLANAR SURFACES AND ADHESIVE-DISPENSING DEVICE USED IN SAID MACHINE ooo#ooo

TECHNICAL FIELD The present invention refers to a machine for the application of fluid adhesive to planar surfaces and to an adhesive-dispensing device used in said machine. In particular, the machine and the above-mentioned device are used with particularly satisfactory results in the laying of floors and tile coverings.

BACKGROUND OF THE INVENTION

As is well-known, tile covering represents one of the most widely used methods on the market for finishing floors and coverings. In particular, a large number of household spaces are still generally tiled, in particular kitchens and bathrooms, but so is also an ever-growing number of industrial or commercial spaces, in particular wherever a high degree of hygiene is required, such as for example in spaces intended for the production and sale of food, as well as in spaces designed for the manufacture of dust-sensitive goods. The market has then further widened when other tile products have been sold beside conventional ceramic products, such tile products being made of plastic-based or wood-based materials also employed in the same laying technique employed for ceramic materials. The most widespread laying technique today, used moreover also for laying fitted carpets or plastic material on rolls (linoleum) , provides the preparation of an evenly-levelled floor foundation or screed on which the tiles are laid and anchored by a suitable fluid adhesive, normally a concrete glue, previously applied to the tiles and/or to the screed.

Glue application represents a particularly critical step of the job, since therefrom depends the satisfactory final appearance of the floor and its stability in time. As a matter of fact, irregularities in the quantity and/or in the thickness of the glue layer determine differences in the height of the individual tiles and the resulting detachment thereof after a

shorter or longer time, both due to the impacts they are subject to as a consequence of the different height thereof, and due to the reduced mechanical resistance of the glue when an excessive amount thereof is applied. Traditionally, and this applies still today to medium- small surfaces, the glue application operation is a manual one. However, it is apparent that, especially for large surfaces such as industrial ones, such manual work is very time-consuming, requires the use of highly skilled labour and inevitably implies gluing irregularities. Moreover, with the current cost of skilled labour, which accounts for a far larger proportion than materials, a similar solution is extremely expensive.

The drawbacks of conventional application systems, however, are not limited to the adhesive application step, but also affect the glue preparation step, wherein glue is typically obtained by mixing two or more powder components with water or other solvents. For example, a powder may be poured into a solvent and a polymerisation trigger for the glue may be added. Since containers and equipment suitable for preparing a mixture with the exact ingredient ratio and with the correct degree of mixing are not easily available on the building site, it happens frequently that adhesive mixes prepared on each occasion differ from one another in density or homogeneity, becoming in turn an element of unevenness in the final covering. Lastly, it must also be borne in mind that, once the mixture has been prepared, the glue has a relatively short life at optimal viscosity, after which the hardening process begins, making the distribution thereof less easy and the gluing less effective, any left-over glue being completely unusable. This calls for the need to provide to the preparation of only small quantities of glue at any one time, with a consequent increase of working time, or it comprises using glue in a less-than- optimal fluidity condition, resulting in unsatisfactory gluing and in the possible waste of hardened, by then useless, adhesive.

In the attempt to overcome these drawbacks, various machines for the automatic application of fluid adhesive have been developed so far, which may be used in the tiling industry. Despite differing from one another, such machines have, however, a common series of drawbacks. In particular, they require the tiles to be fed to the machine continuously for glue application, thereby requiring the presence of an operator dedicated to the task. Stopping or slowing down the feeding, due to various reasons (stock depletion, change of personnel, presence of defective tiles and the like) may hence lead to glue waste or to an undesired build up thereof on one or more tiles . Moreover, the structure itself of these machines makes it difficult to maintain optimal glue fluidity conditions and often involves the presence of hardened glue in machine components, even on the visible face of the tile, which is obviously unacceptable. Finally, the cleaning of such machines currently cannot occur but through water jets, which may entail a risk of electrocution or of short-circuits when electric power to the machines is not previously deactivated according to safety standards .

SUMMARY OF THE INVENTION

The object of the present invention is hence to provide a machine for the application of fluid adhesive to tiles, which allows to achieve an automatic production of tiles whereto the adhesive has been applied, in the desired quantity, without the need of an operator dedicated continuously to machine feeding, without glue hardening problems or problems deriving from soiling of machine components and with the opportunity of automatically adjusting production speed according to the tile layer's requirements, which may vary over time.

Another object of the present invention is to provide, more in general, a machine having the positive features recalled above for the automatic application of adhesive to planar surfaces, for example directly to the screed whereon tiles, covering elements on rolls and the like are to be applied.

A further object of the present invention is to provide a dispensing device of the fluid adhesive which allows to achieve even and adjustable adhesive dispensing, as well as to quickly interrupt adhesive flow, both at the end of the process and during any longer interruptions, and which finally allows to keep the glue in optimal fluidity conditions, regardless of the time employed for using the same.

According to the present invention, the objects set forth above are brilliantly solved by a machine and a device having the features set out in the accompanying independent claims . BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will in any case be better described in detail with reference to an embodiment of the same, illustrated in the accompanying drawings, wherein: fig- 1 is a perspective view of the machine for the application of fluid adhesives according to the present invention, complete with the dispensing device,- fig. 2 is a front and section view of the machine of fig. 1, without the dispensing device, showing the operation of the tile alignment guides,- fig. 3 is a front and section view of the machine of fig. 1, without the dispensing device, illustrating the operation of the tile lifting assembly; fig. 4 is a transversal and section view of the machine of fig. 1, without the dispensing device, which illustrates the transversal moving assembly of said device; fig. 5 is a diagrammatic, front elevation view of the actuating assembly of the dispensing device,- figs. 6 and 7 are top and bottom perspective views, respectively, of the adhesive-dispensing device of the present invention,- fig. 8 is a cross-section view of the dispensing device of fig. 6; fig. 9 is an exploded view of the dispensing device of fig. 6;

fig. 10 is an enlarged-scale view in an open-shutter position of the dispensing bar of the dispensing device of fig. 6 ; and fig. 11 is an enlarged-scale view in a closed- shutter position of the dispensing bar of the dispensing device of fig. 6. BEST WAY TO CARRY OUT THE INVENTION

As is clearly visible in the drawings and in particular in fig. 1, the machine according to the present invention comprises a support casing 1 made of any stiff material suitable for the object, i.e. having mechanical features suitable to support the weight of the tile storage compartment and to bear with no evident deformations the stresses imparted to the machine casing by the automation elements anchored to the same. Preferably, said stiff material is a metal, such as iron, steel and alloys thereof, aluminium, light alloys and other similar materials.

However, also plastic materials may be used, such as, for example, polyethylene, polyethylene-terephtalate, ABS, polystyrene, polyacetate, polyvinyl-chloride and others, either on their own or charged with fillers or, if necessary, with metal profiles. In any case, for casing 1, the stiffness rigidity being the same, a box-like structure is preferred because it is lighter.

Casing 1 bears a base plane 2 supporting two side shoulders 3 and a rear wall 4 and is integral therewith, thereby marking a wide inner compartment having a U-section on a horizontal plane, meant to be used as tile storage, said compartment being fully open towards the front of the machine to make loading and unloading operations as easy as possible. Of course, the machine according to the present invention can be used, in addition to the application of adhesive on conventional tiles of ceramic material, also for the same operation on any type of planar, stackable object having a substantially rectangular shape, such as panel elements, elements for floorings made of fitted carpet or plastic materials, elements of wooden floorings, and the like.

Preferably, casing 1 is supported on two pairs of spinning wheels, whereof two are fixed wheels (not shown in the drawing) and two are pivoting wheels 5, so as to allow full mobility of the machine both in the basic, manual movement version, and in the power version. In this latter version - which may be advantageously employed as movable storage for an automatic tile-laying machine according to WO2004/074 599, also in the name of the same Applicant - the pair of non-pivoting wheels is powered by two independent motor reducers (not shown) which allow, with a suitable adjustment of the force and direction of rotation of the run thereof, to obtain all the possible, desired machine movements. The movement of the above-said motor reducers is software-controlled by a processing unit housed within the machine, according to a programme set by the user, and possibly also according to a "catch-up" mode of an automatic tile-laying machine of the type described in the above-cited patent.

Inside the storage compartment of the machine of the present invention there is housed a vertically displaceable support plate 6, whereon at the beginning of the process the tiles or the other objects are stacked, onto which the adhesive is to be applied. The vertical displacement of support plate 6 is guaranteed by a pair of worm screws 7, which are also housed inside the storage compartment, as can be seen more clearly in fig. 3, whereto plate 6 is connected by means of respective nut- screws. Worm screws 7 are supported at the opposite ends by suitable bearings and driven into rotation by a single motor reducer 8, preferably of the stepping type, by means of a horizontal shaft 9, at whose opposite ends said screws are coupled, with the lower ends thereof, by means of two bevel gear pairs. The displacement of motor reducer 8 and, consequently, of worm screws 7 and of support plate 6, is controlled by the machine processing unit together with end-run sensors, so as to keep the upper element of tile stack P in a well-defined area of the compartment, in close proximity of the adhesive-dispensing device described in the following. Generally, support plate 6 is made of the same material as casing 1, but it can be made of any

other, preferably stiff, material capable of bearing the weight which is applied thereto.

The machine according to the present invention can operate with variously-sized tiles and, in order to achieve correct positioning of the same, guides 10 are advantageously provided on the side and rear walls marking the storage-compartment, which guides are intended to come into contact with the tile edge during their displacement back up into the compartment allowing exact arrangement and displacement of the tiles or of other objects approaching the glue-dispensing device. The position of guides 10 can be adjusted according to requirements; in particular, while the rear guide (not shown) consists of one or two parallel and vertical bars which limit a resting plane of the tile edge, each of the lateral guides 10 preferably consists of metal profiles hinged in the proximity of the base of walls 3 and hence suitably capable of being tilted inwards of the storage-compartment with their upper ends.

That is, as visible in fig. 2, such guides can take up a vertical home position 1Or, wherein loading of the storage compartment is performed with a certain freedom in the lateral positioning of the tiles, and a symmetrically-inclined position 101 wherein the distance between the free ends of guides 10 matches exactly the width of the tiles being processed, so that during the progressive lifting of the stack, the top tiles are positioned on each occasion in an increasingly accurate manner up to a perfectly centred position when they arrive at the position wherein the adhesive is applied. In order to obtain a perfectly symmetrical tilting of lateral guides 10, these are coupled with a same horizontal, freely pivoting, threaded bar 11 which is suitably anchored to walls 3 of the machine. Bar 11 has a left-hand screw thread in a semi -portion thereof and a right- hand screw thread in the opposite semi-portion, so that the rotation thereof in one direction, through handwheel 12, causes opposite, lateral guides 10 to come closer, and to move apart in case of rotation in the opposite direction. Guides 10 are preferably made of a suitable, wear-resistant metal material,

whose surface in contact with the tiles is machined so as to offer low friction resistance and is possibly coated with a low- friction-coefficient, synthetic material _> for example a Teflon- based, silicone-based or similar material. Above machine casing 1 and hence above the storage compartment there is finally housed the adhesive-dispensing device, which comprises a box 20, capable of containing the adhesive to be applied to the tiles and a pressor piston 21 for determining the outflow of adhesive from the box. Box 20, made of the same material as casing 1 or of any other stiff material, is anchored to a movable arc 13, slidable back and forth along the upper edge of lateral walls 3 of the machine, by means of a chain system 14 actuated by a motor reducer 15 (fig.

4) . Also motor reducer 15 is of course controlled by the machine processing unit, in order to adjust the run of box 20 and the translation speed thereof according to the type of tile being processed and to the quantity of adhesive to be applied on the same. Preferably, box 20 can be introduced in and removed with quick-fitting systems "from mobile arc 13, in order to aid adhesive filling and head cleaning operations.

Box 20 has on the bottom a transversal slit wherein a dispensing bar 23 is sealingly housed. As better visible in figs. 7, 10 and 11, said bar 23 has a series of jet holes for adhesive distribution, possibly equipped with side millings to determine the outflow of a line of adhesive with grooves which may vary depending on use. Bar 10 may be made of a metal material, such as steel or aluminium, or a stiff plastic material, such as polystyrene or ABS. Bar 23 is further longitudinally drilled perpendicularly to the direction of the jet holes and inside such longitudinal hole a cylindrical shutter 24 is tightly fitted, itself equipped with a series of transversal through-holes, matching exactly the ones formed in dispensing bar 23. The radial position of shutter 24 can then be easily changed by acting on a transversal grip 25 of the same, thereby changing from a dispensing condition, illustrated in fig. 10, to a non-dispensing position, illustrated in fig. 11,

wherein any possible entry of air in tank 20 through bar 23 is prevented. Operation of the dispensing device can hence be interrupted and continued at will by the operator according to his requirements without causing any deterioration of the glue contained in tank 20, shutter occlusions or undesired soiling of the machine or of the tiles through adhesive.

In a first embodiment of the invention, the conventionally-prepared adhesive is freely poured into tank 20, which is then sealed air-tightly, hence providing a much longer useful life of the adhesive than that offered by conventional use.

In a second, more - advantageous embodiment of the invention, inside tank 20 an air-tight cartridge C is arranged instead, consisting of flexible or semi-rigid material, already filled with ready-to-use adhesive on the manufacturing site and which steadily and sealingly incorporates, in correspondence of a larger outer surface thereof, a dispensing bar 23 of the above-described type. Preferably, cartridges C of a synthetic material are employed, for example a plastic or elastomeric material. A preferred plastic material is polyvinyl-chloride, but other materials can also be used, for example biodegradable or recyclable plastic materials. In order to increase the wear- resistance of cartridges C, the material they consist of can be fabric-finished or otherwise reinforced or coated. There are multiple advantages in employing cartridges C. Firstly, that of fully avoiding the adhesive-preparing step and any form of soiling of the machine and consequent cleaning operations on the same. As a matter of fact, tank 20 now only serves as a container of cartridge C, and of bar 23 of the same which engages with the suitable slit provided in the lower portion of tank 20.

Secondly, the useful life of the adhesive at this point is endless. As a matter of fact, cartridges C are completely airtight both before and during use and can hence be used with no time constraint. As a matter of fact, it must be noted that before using cartridge C the longitudinal hole of dispensing bar

23 is permanently closed by a cylindrical cap shaped like shutter 3, but of course free of holes. Upon use, such cap is slid off and replaced by a shutter 3 (arrow F of fig. 9) . The hole diameter of shutter 3, their number and their overall transversal size can of course be varied in order to adapt the dispensing device to specific uses or specific tile sizes without any other changes to the device itself being necessary.

The dispensing device according to the present invention, as already said, also comprises a pressor piston 21 which, in the two different embodiments described above, will act directly on the adhesive, in the one embodiment, or on cartridge C, in the other embodiment, to let the adhesive flow out from dispensing bar 23. In both cases piston 21 comprises a vertical rod 22 on whose side surface a rack is formed. Through this rack, rod 22 is controlled, in a manner well-known per se, by a motor reducer 28. The assembly consisting of motor reducer 28 and of rod 22 is housed in a box 29 and in a bush 30, respectively, integral with moving arc 13. Also motor reducer 28 is controlled by the machine processing unit, according to a preset programme which adjusts the dwindling speed of piston 22 according to the displacement speed of moving arc 13, to the transversal size of the tile (whereon of course the useful width of the holes of shutter 24 is gauged) and to the amount of adhesive to be applied to the tile. The operation of the automatic adhesive-application machine according to the present invention is of course fully intuitive based on the preceding description. As a matter of fact, the storage compartment of the machine is first loaded with a series of tiles P, stacking the same on support plate 6, so that they abut against the guides provided on the rear wall of the compartment. Then the guides 10 provided on the side walls are displaced from position 1Or to position 101 and tank 20 is filled with adhesive in either of the two ways described above. At this point the machine is ready for use, of course after having suitably programmed the processing unit with the variable data of the tiles and with the desired amount of glue.

Upon operation of the START control, mobile arc 13 begins the run from the rear portion of the machine to the front one, while piston 21 is displaced to the bottom of tank 20 (arrow G pointing downwards in fig. 8) to allow the outflow of adhesive from dispensing bar 23. Once it has arrived at an end stop, caused by a sensor according to tile length, mobile arc 13 returns into home position, while the pressure of piston 21 had been released with a certain advance (arrow G upwards) to allow the halt of glue dispensing in correspondence of the tile front edge. At this point tile P can be collected by the operator for laying, with no time constraint. That is, the operator can collect said tile from the machine as soon as the adhesive has been applied to the same, or at a later time, depending on the processing requirements thereof; as a matter of fact, until the tile is collected, the machine performs no further operation.

Upon collection, the machine detects that the top level of the tile stack is lower, and hence provides to activate motor reducer 8 to raise the top tile to the correct level, then activating a new run of mobile arc 13 and of adhesive dispensing .

The present description has been supplied with special reference to a machine for the application of adhesive to tile elements, but it is clear that the dispensing device used in this machine can be used in different machines for other adhesive-dispensing modes, for example to dispense the adhesive directly on to the screed, by means of a self-propelled machine which bears the dispensing bar at floor level and has no tile storage nor the corresponding lifting system. Such a type of machine is hence specifically comprised in the scope of protection of the present invention.

Equally comprised in the scope of protection of the present invention must be intended all the variants and improvements of the preferred embodiment of the above-described adhesive application machine, which are within the obvious reach of a person skilled in the field in the light of the teachings supplied here, as defined in the accompanying claims.