Adhesive spreading unit provided with a roller-cleaning device

An adhesive-spreading assembly includes a plurality of rollers (R), that rotate in contact with one another to transfer a thin layer of adhesive from a tank (T) onto a film in motion, complete with a device for cleaning the rollers (R), removably connectable to the adhesive-spreading assembly and including at least one tank (5, 6) containing at least one cleaning fluid and pumping elements (8) for transferring the fluid to distributor elements (12) for delivering a part of the fluid onto the surface of the rollers (R). The adhesive-spreading assembly includes a transfer system (15) designed to transfer the distributor elements (12) in a direction substantially parallel to the axis of the rollers to distribute the fluid over their whole surface, the transfer system being configured so that it can be removably coupled with the distributor elements.

The present invention relates to an assembly for spreading an adhesive and, more in particular, to an adhesive-spreading assembly of the type used in coupling machines or the like, complete with a device for cleaning the adhesive-spreading rollers.

It is common knowledge that the machines used for coupling several films (possibly made of different materials) together include means for spreading an adhesive comprising a plurality of rollers that rotate in contact with one another so as to transfer a thin layer of adhesive onto a film in motion.

An adhesive-spreading assembly of this type is described in the European patent application EP 2.085.219 lodged by the same applicant.

In detail, said known adhesive-spreading assembly comprises at least a first roller designed to collect adhesive from a tank and transfer it to a second roller that moves at a faster speed so that the layer of adhesive collected on the latter is thinner; the second roller is likewise designed to transfer the adhesive to a third roller turning at an even faster speed, that is slidingly in contact with the film to be coupled and thus deposits the adhesive thereon.

Every time the machine is stopped for a period of time, e.g. when production is temporarily interrupted, or to allow for servicing procedures, the adhesive-spreading rollers must be cleaned to avoid the adhesive drying on their surface and making it impossible to use them when the machine is started again.

In particular, to ensure the utmost adhesive-spreading efficiency and precision, all traces of adhesive must be removed from the rollers to avoid it drying and altering the rollers' original surface roughness, and the subsequent spreading process as a consequence.

These cleaning procedures are currently performed manually by one or more operators who have to access the inside of the coupling machine through safety hatches in order to reach the rollers.

In detail, the cleaning procedure involves pouring specific cleaning fluids onto the rollers and rubbing their surfaces with cloths or the like.

To make this procedure easier for the operator, the rollers are turned slowly by means of a manual control so that their whole surface can be reached from the same position.

The above-described cleaning procedure has numerous drawbacks, however.

First of all, it is the not very efficient because, being done entirely by hand, it demands the use of manpower for several dozen minutes.

In fact, given the above-described unfavourable working conditions, the operator takes a considerable amount of time to complete the cleaning procedure reasonably effectively.

Using this method, the safety issues for the operator completing the cleaning procedure are also far from negligible.

As already mentioned, the operator is obliged to go inside the machine, disabling all of the safety devices in order to do so, and to work in the vicinity of mechanical parts in motion, with the related risks that this entails (i.e. the risk of the operators' clothing becoming entangled, or even of their hands being crushed between two counter-rotating rollers).

In addition to the above, the operator is obliged to work in close contact with cleaning fluids that consist of chemical products containing solvents, which are harmful if inhaled and irritant in contact with the skin.

In the light of the above, the object of the present invention is an adhesive-spreading assembly that overcomes the drawbacks of the known state of the art.

In detail, the object of the invention is an adhesive-spreading assembly with a roller-cleaning device that enables the above-described roller-cleaning procedure to be completed entirely automatically.

To be more precise, the object of the invention is an adhesive-spreading assembly with a roller-cleaning device that does not require the use of manpower and that ensures a higher level of operator safety.

A further object of the present invention is an adhesive-spreading assembly with a roller-cleaning device that not only takes less time to complete the cleaning procedure, but also ensures an optimal cleaning of the rollers.

Another object of the present invention is an adhesive-spreading assembly with a roller-cleaning device that is simple to manufacture, inexpensive and requires no modification of the known coupling machines with which it is associated.

Another object of the present invention is an adhesive-spreading assembly with a roller-cleaning device that can be quickly and easily attached to and removed from the adhesive-spreading assembly to reduce the machine outage times to a minimum.

The above-mentioned objects are substantially achieved by an adhesive-spreading assembly with a roller-cleaning device according to one or more of the attached claims.

In particular, the objects are achieved by an adhesive-spreading assembly comprising a plurality of rollers that rotate in contact with one another to transfer a thin layer of adhesive from a tank onto a film in motion, and complete with a device for cleaning said rollers for removably attaching to said adhesive-spreading assembly, comprising at least one tank for at least one cleaning fluid, pumping means for delivering said fluid to distributor means designed to apply a part of said fluid to the surface of the rollers, characterised in that said adhesive-spreading assembly comprises a transfer system designed to move said distributor means in a direction substantially parallel to the axis of the rollers to distribute said cleaning fluid over their whole surface, said transfer system being designed to be removably coupled to said distributor means.

Using the device configured as above, the cleaning device can be attached to the adhesive-spreading assembly as and when it is necessary to clean the rollers, and particularly to remove all residual traces of adhesive quickly and completely automatically, thanks to the transfer system.

Said system for transferring the distributor means also ensures an even distribution of the cleaning fluid over the whole surface of the rollers, guaranteeing the utmost efficacy of the cleaning procedure.

According to the invention, said transfer system may comprise a bearing element mounted slidingly on a guide and driven by means of one or more actuators along an axis substantially parallel to the axis of the rollers in the adhesive-spreading assembly.

According to a preferred embodiment, said bearing consists of a body shaped to be removably coupled with a distributor head. This enables the cleaning device to be attached only during cleaning procedures and to be removed during the normal operation of the machine, thus reducing the machine's footprint.

More in detail, the body of the bearing may include a seat designed to contain a pin attached to the distributor head and projecting therefrom, for connecting to the seat with the aid of suitable locking means.

The bearing body thus configured enables the transfer device to be used to attach both the cleaning fluid distributor head and the adhesive dispenser head during the normal operation of the machine, thereby enabling the structural complexity of the machine to be reduced.

With reference to the attached figures, the adhesive-spreading assembly, indicated globally by the letter G, comprises a plurality of rollers R that rotate in contact with one another to transfer a thin layer of adhesive from a tank T onto a film F in motion, e.g. in a coupling machine or the like.

According to the invention, the adhesive-spreading assembly is complete with a cleaning device1, comprising a supporting structure2, preferably with rolling means to facilitate its displacement when it has to be juxtaposed with the adhesive-spreading assembly to complete the cleaning procedure.

In the embodiment illustrated, said structure2comprises a wheel-mounted trolley3, with a platform4on which the various components are installed.

According to the invention, the device comprises at least one tank, located on said platform, for containing a cleaning fluid, e.g. solvents or the like, suitable for removing adhesive from the surface of the rollers R in the adhesive-spreading assembly G.

The cleaning device preferably includes a pair of tanks5and6, containing a reagent fluid and a solvent fluid, respectively.

Said tanks are connected by piping7to pumping means, indicated globally by the numeral8, for delivering said fluid to the surface of the rollers R.

The pumping means8can be connected to control means serving a coupling machine.

In a preferred embodiment, said pumping means comprise a pneumatically-controlled diaphragm pump9. Better still, said pump is a double-diaphragm pump because a pump of this type guarantees high safety standards in the presence of flammable liquids such as solvents or the like.

To ensure proper operation, said pump is positioned on a level higher than the surface of the fluid(s) in the tanks5and6. For this purpose, the trolley comprises a supporting element with a raised shelf10on which the pump is anchored.

To enable the delivery of only one fluid at a time (only the reagent or only the solvent), there is an on/off valve11on each pipe7connected to the tanks5and6. Thus, when the pump is operating, its suction line is only connected to one of the two tanks.

The operation of the valves11, and of the valve that enables the pump9, is preferably controlled by a suitable cleaning program input in the PLC used to manage the coupling machine on which the adhesive-spreading assembly is installed.

Alternatively, the device may be fitted with its own control unit (not shown in the figure), connected to said valves and possibly to the PLC serving the coupling machine in order to communicate therewith.

The pump9is connected on the delivery side with distributor means, indicated globally by the numeral12, designed to distribute the cleaning fluids on the surface of the rollers in the adhesive-spreading assembly.

More in detail, said distributor means comprise a distributor head13connected to the pump9by means of piping14.

On said distributor head, there are also one or more outlet pipe(s)17, complete with a nozzle for positioning in the vicinity of the surface of the various rollers.

Said piping17is preferably rigid piping, suitable for retaining a pre-set shape or a given curvature.

A characteristic of the invention lies in that it includes a transfer system, indicated globally by the numeral15, designed to transfer said distributor head13in a direction substantially parallel to the axis of the rollers.

Said distributor head13can thus be moved alternately from one end of the rollers to the other to enable an even distribution of the cleaning fluids over their whole surface.

More in detail, said transfer system15may comprise a bearing16slidingly installed on a guide24and driven by means of one or more actuators18, such as pneumatic actuators or the like.

According to the embodiment illustrated, the bearing16comprises a body shaped so that it can be removably coupled with the distributor head13.

In detail, said body includes a seat21, designed to contain a pin22extending from the distributor head13, blocking means such as a screw or the like being provided to connect said two elements firmly together.

The body of the bearing16preferably comprises rolling means20for sliding along the guide24.

According to the invention, the transfer system15can be juxtaposed with the outer casing C of the adhesive-spreading assembly on a coupling machine so that only the outlet pipes17on the distributor head are inside the machine, up against the rollers.

Said transfer system may be attached to the machine in a fixed or movable manner, according to need.

FIG. 1shows the adhesive-spreading assembly complete with the roller-cleaning device according to the invention in the working configuration.

In an adhesive-spreading assembly of this type, the tank T of adhesive occupies the volume coming between the surfaces of the first two rollers, which are counter-rotating.

Generally speaking, the adhesive is dispensed continuously in this area by means of a dispensing head connected to a suitable adhesive supply system, generally located outside the machine.

To facilitate an even distribution of the adhesive over the full length of the rollers, it is necessary here again to use a transfer system designed to move the dispensing head (not shown in the figure) from one end of the rollers to the other.

In this case, said transfer system15according to the invention can be used both to transfer the distributor head13during the roller-cleaning procedure, when the machine is not in use, and to transfer the adhesive-dispensing head.

More in detail, the seat21in the body of the bearing16may contain either the pin22on the distributor head13or a particular part on the adhesive-dispensing head, e.g. a pipe or the like.

This enables the roller-cleaning device to be attached to adhesive-spreading assemblies already fitted with a transfer system, without needing to make any changes and with a further saving of manufacturing costs.

The procedure for cleaning the rollers R in the adhesive-spreading assembly using the device according to the invention is extremely quick and simple.

In fact, it is only necessary to juxtapose the device with the machine and place the pipes17with the nozzles up against the surfaces of the various rollers.

Then a cleaning program memorised in the PLC serving the coupling machine can be used to operate the pump9and the corresponding valves11to dispense the cleaning fluid on the surfaces of the rollers.

In detail, it is preferable to dispense the reagent fluid first, and then the solvent fluid after an interval established by the program.

During the cleaning procedure, the rollers are preferably turned so as to coat their whole surface with the cleaning fluids.

To limit the number of pipes17needed, the rollers are turned in contact with one another so that one pipe suffices to ensure an adequate distribution of the fluid on the surfaces of at least two adjacent rollers.

Then the rollers are separated and turned again to enable all adhesive residues and cleaning fluid to pour into a suitable collection tank V underneath (already used as part of the adhesive-spreading assembly).

The rotation and displacement of the rollers are also controlled automatically by the program saved in the PLC serving the machine.

It is clear from the above description that the adhesive-spreading assembly with a roller-cleaning device according to the invention enables the rollers to be cleaned completely automatically, quickly, and without the need for any manpower.

In particular, this cleaning procedure only requires an operator to take action on the device by means of the PLC on the machine, consequently eliminating all the safety issues involved in the known cleaning method.

In addition, the adhesive-spreading assembly does not need to undergo any costly modification, by comparison with the known adhesive-spreading assemblies, in order to attach the cleaning device.

The present invention, as described and illustrated above, is liable to numerous modifications and variants, all coming within the scope of the inventive concept; in addition, all the component parts may be replaced by other technically-equivalent elements.