FR3075763A1 - WELDING DEVICE AND METHOD FOR WELDING THERMORETRACTABLE FILMS ENRICHING LOTS OF OBJECTS IN A FARDING PLANT - Google Patents

Abstract

The present invention relates to a soldering device 10 for welding heat-shrinkable films 12 coating batches 14 of objects 16 simultaneously to their conveying in a rigging installation 1 comprising: - a conveying means 18 of said batches 14, the ends of the film 12 coating each batch 14 being superimposed under said batch 14, said conveying means 18 being able to move the batches of objects in the direction of travel of the batches in the wrapping installation and in a conveying plane 20, and - at less a radiation energy source 24 capable of welding the heat-shrinkable film 12; characterized in that said conveying means 18 comprises at least one window 22 adapted to move with said conveying means 18 and in that said energy source 24 is fixed on a support 25 placed under the conveying plane 20 and is adapted to move in the same direction as said conveying means 18 and independently, so as to weld through said window 22.

Description

Welding device and method for welding heat-shrinkable films coating batches of objects in a wrapping installation.

The present invention relates to the field of wrapping equipment and methods, which use a strip of heat-shrinkable film to coat an object or a batch of objects, such as bottles, with a heat-shrinkable film, and form, for example a pack of bottles.

It relates, more particularly, to a device and a method for welding together the two upstream and downstream ends of a strip of film coating the batch of objects. The film wrapping of objects is a widespread technique, which allows several objects to be grouped together, such as bottles, flasks, boxes, jars, or any other type of object. This technique makes it easier to transport objects to a place of final destination where the packaging is removed. Depending on the type of wrapped objects, either the film is the only element of the packaging, or it is associated with additional elements, such as plates, trays or the like on which the objects are placed before being placed under movie. The invention particularly relates to the packaging in batches of bundled objects through a bundling step, said objects passing through a shrinkwrapper module.

More specifically, a shrinkwrapper is continuously fed by a stream of objects, advancing on a conveyor along several parallel lines. In order to arrange several objects in each of said lines in batches, a shrinkwrapper includes a selection station, commonly known as a "cassette", ensuring the grouping of said objects in batches and the separation between successive batches.

The batches formed are generally organized in a rectangular matrix with or without hardware. These lots therefore have in principle rectangular edges, several products extending along each of the two edges.

The formed batches are transferred to a conveyor of a so-called “topping” station, making it possible to coat each batch of objects by means of heat-shrinkable film. Said topping station ensures, on the one hand, the feeding and cutting of a film reel into film sheets, from a film reel according to a length corresponding to the dimensions of said objects and to the size of each batch. and, on the other hand, the covering of each batch of objects by said sheet of film at the posterior, upper, anterior and lower faces (said posterior and anterior faces lying reciprocally upstream and downstream with respect to the direction of scrolling of said objects). The side faces are therefore not covered, while each batch of objects is coated from rear to front.

The film sheets, once sectioned, are sent to a topping station via a so-called "injection, cutting" station, which allows each sheet to be moved to the conveyor of the lapping station, so synchronized with the transfer of batches of objects from the selection station. In particular, this transfer takes place so that the downstream end of each sheet comes to rest on the surface of the topping conveyor and is pinched by the weight of the objects transferred at the same time from the selection station, in particular at the bottom. objects in the upstream part of each batch (after coating, the opposite upstream end of the sheet can then be pinched in particular by the objects in the downstream part of each batch at the time of transfer out of said coating conveyor).

In principle, there is a zone of overlap of the upstream and downstream ends of the film which coats a batch, under said batch.

Once the batches have been covered with their film sheet, they pass through a heating station, consisting of at least one heat-shrinking tunnel. The material of said film is provided heat shrink, allowing each sheet under the action of heating to match the external shape of the batch of objects, holding them together. The batch thus coated and enclosed by said shrunk film is cooled at the outlet of the oven, in order to impart sufficient mechanical strength to the burden thus kept coated for handling and transport.

More specifically, the film is heat-shrunk around the batch of objects by passing through a heat-shrinking tunnel. To carry out the heat-shrinking of the heat-shrinkable film, the heat-shrinking tunnel comprises heating members which make it possible to reach a temperature which is between 150 ° C. and 250 ° C. depending on the wrapped objects and according to the type of heat-shrinkable film used; generally this temperature is of the order of 200 ° C.

The heat-shrinking tunnel comprises a conveying means provided with an endless chain which can be made of steel or plastic or else of a composite material. The batches of objects are placed on the endless chain to be conveyed in the heat-shrinking tunnel. Thanks to the temperature prevailing in the heat-shrinking tunnel, the endless chain rises in temperature to weld the ends of the film together. However, to carry out this welding operation, a dedicated ventilation of hot air crosses the endless chain during its circulation in the heat-shrinking tunnel to accumulate a significant quantity of calories in order to raise its temperature which will also have the effect of welding the two ends of the film. When entering the heat-shrinking tunnel, the chain absorbs calories, while exiting, the chain returns these calories to the atmosphere. Consequently, the thermal balance of such a heat shrink tunnel is relatively poor, especially since this hot air intended for welding is blown continuously when the shrink tunnel is in operation.

It is therefore necessary to propose a solution which makes it possible to improve the overall thermal efficiency of the bundling installation and in particular the welding function which is extremely energy consuming.

To do this, the invention proposes to weld the ends of the film coating the batch of objects with a source of energy by radiation so as to provide just the energy necessary for its realization. Furthermore, the fact of having separated the function of sealing the ends of the film with the function of shrinking the film by the heat-shrinking tunnel makes it possible to be able to optimize each function. Finally, when the installation is stopped, the welding device, in particular the energy source, stops instantly. Similarly, when the installation is restarted, the welding device, in particular the energy source, is immediately operational. Consequently, the welding device is not penalizing for restarting the installation. To this end, the subject of the invention is a welding device for welding heat-shrinkable films coating batches of objects simultaneously with their conveyance in a wrapping installation comprising: - a means for conveying said batches, the ends of the film coating each batch being superimposed under said batch, said conveying means being able to move the batches of objects in the direction of travel of the batches in the bundling installation and in a conveying plane, and - at least one energy source per radiation capable of welding the heat-shrinkable film.

This device is characterized in that said conveying means comprises at least one window capable of moving with said conveying means and in that said energy source is fixed on a support placed under the conveying plane and is capable of moving move in the same direction as said conveying means and independently, so as to produce a weld through said window. The invention also relates to a method of welding heat-shrinkable films coating batches of objects simultaneously with their movement along a direction of travel in a wrapping installation; said method comprising for each batch a step of coating said batch of objects with a heat-shrinkable film whose ends of the upstream and downstream film are superimposed under said batches so as to provide a zone for covering the ends of the film.

This process is characterized in that it comprises, for each batch, subsequent to the coating step, at least the following steps: -positioning at least part of the area for covering the ends of the film on a transverse window with respect to in the direction of scrolling; -maintain the window under said overlap zone by moving it in the direction of travel at the same speed as said batch; and positioning a source of radiation energy under said window and emitting radiation at the level of the overlap zone through said window. The invention will be better understood thanks to the description below, which is based on possible embodiments, explained in an illustrative and in no way limitative manner, with reference to the appended figures, in which: - Figure 1 is a view of schematic side of a wrapping installation provided with a welding device according to an embodiment of the invention; - Figure 2 is a schematic perspective overview with a welding device according to one embodiment of the invention; - Figure 3 is a side view of a welding device according to a first embodiment; - Figure 4 is a side view of a welding device according to a second embodiment.

In the following description, we will adopt, without limitation, orientations: longitudinal directed along the direction of travel of the objects conveyed in a wrapping installation 1 or vice versa, and transverse directed along the perpendicular to the direction of travel Objects. The invention therefore firstly relates to a welding device 10 for welding heat-shrinkable films 12 coating batches 14 of objects 16 simultaneously with their conveyance in a wrapping installation 1 comprising: - a conveyor means 18 for said batches 14, the ends of the film 12 coating each batch 14 being superimposed under said batch 14, said conveying means 18 being able to move the batches of objects in the direction 28 of movement of the batches in the wrapping installation 1 and in a conveying plane 20, and - at least one energy source 24 by radiation capable of welding the heat-shrinkable film 12;

Objects 16 are preferably of the vial, bottle or other type, notably containing liquid. Within a bundling installation 1, these objects are grouped in batches, then each batch is coated with a film which is then shrunk around said batch so as to form a self-supporting burden. The batches of objects are each formed of at least one row, transverse to the direction 28 of movement of the batches in the bundling installation, and of at least one longitudinal column in the direction of 28 movement of the batches in the wrapping installation. Furthermore, these objects in a lot 14 can be staggered.

Conventionally, a wrapping installation 1 comprises a selection station 34, an injection station (not shown), a coating station 36 and a heat shrink tunnel 32. The welding device according to the invention is located between the coating station and the heat-shrinking tunnel.

The batch 14 of objects is formed at the wrapping installation by the selection station 34, generally in the following manner. This selection station 34 includes an upstream conveyor which brings the objects continuously to order. These objects are generally arranged in columns, or rows, and are guided in longitudinal corridors with respect to the direction 28 of scrolling of the objects, a downstream conveyor which contributes to shaping the batch 14 of objects according to a precise diagram, and a device for regulation located between the upstream conveyor and the downstream conveyor of the selection station. Advantageously, this regulating device channels the objects in corridors delimited by side walls, a sole, and a system of retractable fingers movable longitudinally continuously and which are temporarily inserted between the objects of the same column to release rows objects on the downstream conveyor to be grouped together to form the batch 14 of objects according to the precise diagram.

The batch 14 of objects formed then passes through a coating station 36 to be coated therewith with a heat-shrinkable film 12. The lapping station 36 is arranged after the selection station 34 and more particularly after the downstream conveyor of the selection station 34. There is a slot 38 between the downstream conveyor of the selection station 34 and the lapping station 36 which comprises a conveyor. A film injection device is generally located below the conveying plane 20 defined by the conveyors on which the objects circulate, and projects through said slot 38 called “injection slot 38”, a downstream end of the film 12 heat-shrinkable, just while the batch 14 of objects is mounted on the conveyor of the topping station 36. Thus the weight of the batch 14 makes it possible to pinch the downstream end of the film 12 between the batch 14 and the conveyor of the coating station 36. The conveyor of the topping station 36 then drives the batch 14 and the downstream end of the film 12 at the same speed. Then, once the batch 14 of objects has completely crossed the injection slit 38, a cycling bar 40 arises from below the conveying plane 20 through the slit 38 and drives the upstream end of the heat-shrinkable film 12. The cycling bar 40 bypasses the batch 14 of objects during its transit on the conveyor of the topping station 36 and passes from the rear of the batch of objects 14 to the top, then descends in front of the batch 14 of objects. The film 12 has been cut beforehand to the dimension adapted to surround the batch 14 of objects. The end of the cycle of the cycling bar 40 brings the upstream end of the film 12 back to the batch 14 of objects. The upstream end of the film 12 then passes under the batch 14 of objects when the batch of objects leaves the conveyor of the coating station to reach the conveying means 18. The upstream and downstream ends of the film are superimposed under the batch 14 of objects thus defining an overlap area 42 which extends over the entire width of the batch which is transverse to the direction of travel of the batches of objects.

Then, after the coating station 36, the batch 14 of objects coated with a film 12 is conveyed by a conveying means 18 to the heat-shrinking tunnel 32. This conveying means 18 will be more detailed in the following description.

Before entering the heat-shrinking tunnel 32 and during their conveying, the ends of the film 12 of each batch are welded at an overlap zone 42 using an energy source 24 by radiation .

All sources of radiation energy capable of welding the ends of a film can be used in the context of the present invention. However, the choice of the energy source 24 is made as a function in particular of the following parameters: the wavelength of the beam, the material of the film 12 to be welded, the exposure time necessary to perform the welding, the beam shape at the output of the energy source 24, the power density of the beam. These various parameters have a significant impact on the quality of the weld which must be produced between the two ends. Those skilled in the art are able to determine an energy source suitable for welding the ends of the film at its overlap area 42.

The energy source 24 is a source of electromagnetic radiation preferably emitting a laser type beam at a certain wavelength.

According to the invention, this device is characterized in that said conveying means 18 comprises at least one window 22 able to move with said conveying means 18 and in that said energy source 24 is fixed on a support 25 placed under the conveying plane 20 and is able to move in the same direction as said conveying means 18 and independently, so as to produce a weld through said window 22.

The term “window 22” means an orifice or passage of generally rectangular shape whose length of the rectangle is in principle transverse to the direction 28 of movement of the batches 14 of objects in the bundling installation, and whose width of the rectangle is in principle longitudinal with respect to the direction 28 of movement of the batches 14 in the bundling installation. This window 22 makes it possible to expose the ends of the film 12 located under the batch 14 of objects to the energy source 24 in order to weld the upstream and downstream ends of the film 12 together before heat shrinking the film 12 on the batch 14 objects through the heat shrink tunnel 32. In general, the transverse dimension of the window relative to the direction of movement of the batches is at least equal to the dimension of the batches along the same direction, so that a weld can be produced over the entire length of the overlap zone . In other words, the length of the window is substantially equal to the length of the overlap area.

The term “conveying plane 20” means the horizontal plane on which the batches 14 of objects move in the bundling installation comprising the welding device.

The window 22 can move with the conveying means 18 which supports the batch 14 of objects and the energy source 24 which is fixed on the support 25, can be movable, and can move in the direction 28 of movement of the lots 14 in the wrapping installation under the conveying plane 20, as well as in the opposite direction.

The window 22 and the support 25 on which the energy source is fixed, are able to move simultaneously in particular in the direction 28 of movement of the batches 14 in the installation to increase the exposure time of the upstream and downstream ends of the film 12 at energy source 24 to weld them together.

The window 22 and the support 25 on which the energy source 24 is fixed can also move independently of one another. These movements can in particular be independent, for example, when the support 25 returns to its initial position to start a welding cycle again and returns to the view of the window or of a new window 22.

The support is the structure carrying the energy source. This support is able to move in the direction 28 of movement of the batches, that is to say in the longitudinal direction of the wrapping installation. In addition, this support is located under the conveying plane 20. According to the embodiment of this support, it can be mounted on a conveyor forming a closed loop so as to operate in continuous mode or on a conveyor forming a linear guide of so as to operate in sequential mode, that is to say back and forth. In continuous mode, during the welding step, the support follows the window 22 and the batch 14 of objects. When the welding step is finished, the support continues its race independently with respect to the window and the batch of objects to return to its initial position and start a welding step again. In sequential mode, during the welding step, the support also follows the window and the batch of objects. When the welding step is finished, the shuttle returns to its initial position to start again a welding step. By way of nonlimiting example, the support can be at least one shuttle circulating on a guide means thanks to a principle of linear motor.

According to the embodiment, this device can have several energy sources and several windows.

In addition, the energy source is not necessarily associated with a specific window.

According to a possible additional characteristic, the energy source 24 is a source of electromagnetic radiation preferably emitting radiation in the infrared range.

Tests have demonstrated that over the entire light spectrum, the radiation useful for welding a thermoplastic material such as PP, PE (materials in which heat shrink films are conventionally produced) is located in the infrared range, that is that is to say for wavelengths between 13900 nm and 6800 nm as well as 6800 nm and 3400 nm which are generally the absorption domains of these materials.

These energy sources are preferably of the laser type. The advantage of this type of source is to generate an interaction between a radiation in a certain wavelength and the material so as to create a faster and more rapid heating in the thickness of the material.

According to another possible additional characteristic, the energy source 24 is able to move transversely relative to the direction 28 of movement of the batches in the bundling installation.

The support on which the energy source 24 is mounted can thus move transversely relative to the direction 28 of travel of the batch 14 of objects. This transverse movement of the energy source 24 can advantageously make it possible to sweep the ends of the heat-shrinkable film over the entire length of the window 22, that is to say, all along the transverse dimension of the overlap zone 42 of the film 12. During this transverse movement, the energy source 24 can also move longitudinally in the direction of movement of batches in the bundling installation in order to remain under the window to increase the duration of exposure of the film to radiation from the power source and also improve the quality of the weld. Consequently, the support on which the energy source 24 is fixed can be animated by a combined movement which is both transverse and longitudinal.

According to another possible additional characteristic, the energy source 24 comprises a set of lenses capable of deflecting the radiation transversely with respect to the direction 28 of movement of the batches 14 in the bundling installation.

The set of lenses is juxtaposed with the energy source 24 and is located between the energy source 24 and the batch of objects to allow the radiation to be deflected over the entire length of the window 22 to weld the ends together, that is to say at the level of the overlap zone 42. In this embodiment, the energy source 24 is fixed and the set of lenses advantageously makes it possible to weld the film over the entire transverse dimension in freedom from a transverse movement of the support. In other words, it is the set of lenses which manages the transverse deviation of the radiation.

Alternatively, the set of lenses can be combined with a transverse movement of the support on which the energy source is fixed.

According to another possible additional characteristic, the energy source 24 comprises a plurality of radiation energy generators.

The welding of the ends of the heat-shrinkable film 12 can be carried out by means of one or a plurality of energy sources emitting the beams of electromagnetic radiation. These beams can be adjacent or juxtaposed. For example, the energy source can have the form of a bar to cover the length of window 22.

The radiation emitted by the energy source can be linear, it is for example directed in a general predetermined direction for example perpendicular to the conveying plane 20. However, a set of lenses can make the radiation diverge.

The structure of the conveying means 18 can be produced in different ways in order to be able to create one or more windows.

According to another possible additional characteristic, the conveying means 18 is formed of an endless band 26 wound around at least two windings 30, said window 22 corresponding to a groove made in the band, said groove being transverse to the direction 28 of scrolling lots 14.

The conveying means 18 comprises an endless belt 26 wound around at least two windings 30 whose axes are transverse with respect to the direction 28 of travel of the batches in the wrapping installation and parallel to each other. In addition, at least one of the winding axes 30 is motorized, for example by a synchronous motor such as a brushless motor so as to constantly know the position of the endless belt 26.

In this embodiment, the window 22 is a through groove made in the mass of the endless belt 26 and forms a hole to allow the radiation to pass. This groove is for example of rectangular shape whose length of the rectangle is transverse to the direction 28 of movement of the batches 14 of objects in the wrapping installation, and whose width of the rectangle is longitudinal with respect to the direction of travel of the batches 14 in the wrapping installation.

In this embodiment, the endless belt can have several grooves over its entire length to allow the rate of this welding device to be increased.

According to another possible additional characteristic, the conveying means 18 comprises at least one shuttle circulating on a guide means capable of moving said shuttle in the direction 28 of movement of the batches 14 of objects of the wrapping installation, thanks to a linear motor principle, said window 22 corresponding to a groove made in the shuttle and transverse with respect to the direction 28 of movement of the batches 14.

In this embodiment, the shuttle is located under the conveying plane 20, that is to say under the batch of objects to be welded. It can be mounted on a guide means forming a closed loop so as to operate in continuous mode or on a guide means forming a linear guide so as to operate in sequential mode, that is to say in round trip. Depending on the operating mode chosen, continuous or sequential, the number of shuttles is very variable. In sequence, the number of shuttles can be only one. Continuously, the number of shuttles depends in particular on the length of the welding device or the rate.

The groove has the shape of a hole and is made in the mass of the shuttle to put in communication the face on which the batch of objects rests and the opposite face. This groove is for example of rectangular shape whose length of the rectangle is transverse to the direction 28 of movement of the batches of objects in the bundling installation, and whose width of the rectangle is longitudinal with respect to the direction 28 of scrolling of the batches in the bundling installation.

According to another possible additional characteristic, the conveyor means 18 comprises at least two conveyors placed one after the other in the direction 28 of movement of the batches 14 of objects, the interface between the two conveyors being movable , said window (22) corresponding to said interface.

The conveying means 18 then comprises at least two conveyors placed in the conveying plane 20, one after the other in the direction of travel of the batches of objects. Each of the conveyors comprises an endless belt 26 wound on at least two windings 30, and the window 22 is defined by the space separating the two adjacent conveyors. More specifically, the window is located between the upstream winding of the downstream conveyor and the downstream winding of the upstream conveyor.

During the welding step, the space forming the window between the upstream winding of the downstream conveyor and the downstream winding of the upstream conveyor advances in the direction of travel of the batches of objects, then moves back once the step welding is carried out. Advantageously, the upstream conveyor lengthens while the downstream conveyor moves back.

The two adjacent windings 30 can be movable longitudinally, in particular simultaneously with respect to each other to keep the size of the window 22 constant during the welding of the two ends and to keep the ends of the film 12 on the window 22. From more, the longitudinal displacement speed of the windings is the same as the displacement speed of the batches of objects.

According to another possible additional characteristic, the conveyor means 18 comprises at least two shuttles circulating on a guide means capable of moving said shuttles one behind the other in the direction 28 of movement of the batches 14, said window 22 corresponding to the space between two successive shuttles. The invention also relates to a process for welding heat-shrinkable films coating batches 14 of objects simultaneously with their movement along a direction of travel; said method comprising for each batch a step of coating said batch 14 of objects with a heat-shrinkable film 12 whose ends of the film 12 upstream and downstream are superimposed under said batches 14 so as to provide a zone 42 for covering the ends of the film 12.

According to the invention, the method is characterized in that it comprises for each batch, subsequent to the coating step, at least the following steps: -positioning at least part of the zone 42 for covering the ends of the film 12 on a window 22 transverse to the direction of travel 28; -maintain the window under said overlap zone by moving it in the direction of travel at the same speed as said batch; positioning a source of energy under said window and emitting radiation at the level of the overlap zone through said window 22.

According to a possible additional characteristic, during the step of emitting the radiation, said energy source moves in the direction of travel at the same speed as said batch.

At the outlet of the topping station, the position of the batch of objects is precisely known thanks to a position sensor. From then on, a control unit makes it possible to synchronize the movement of the batch of objects leaving the coating station and entering the welding device, that is to say on the window. Once the batch of objects is correctly positioned on the window, the energy source can start to emit. Then, the batch of objects resting on the window, as well as the energy source can start to move in the direction of travel and all at the same speed during the welding step.

According to another possible additional characteristic, during the step of emitting said radiation, said energy source moves transversely to the direction of travel so that the welding is carried out over the entire dimension of said batch transversely to its direction of scrolling.

According to another possible additional characteristic, the heat-shrinkable film 12 used is a radiation-absorbing film.

With this type of energy source welding device, the heat-shrinkable film must absorb all of the radiation emitted by the energy source to avoid degradation of the objects and also to reduce the time required to weld the film.

According to another possible additional characteristic, the method further comprises, prior to the coating step, a step of coating the ends of the film (12) with a radiation-absorbing material, such as carbon black.

A carbon black coating step can be carried out on the upstream and downstream ends of the film and more particularly at the level of the overlap zone. This step can be carried out upstream of the welding device.

As explained previously, the use or the fact of coating the ends of the heat-shrinkable film 12 with an absorbent product such as carbon black before the welding is carried out makes it possible to avoid certain radiation from passing through the heat-shrinkable film 12 and thus coming degrade the objects forming lot 14.

According to another possible additional characteristic, the method further comprises the following step, placing the batch 14 of objects on a particularly cardboard plate, before coating the batches of objects with a film 12.

The positioning of a plate before coating the heat-shrinkable film 12 around the batch 14 has in particular the function of protecting the batch 14 of objects from radiation.

According to another possible additional characteristic, during the emission of the radiation, the power of the radiation emitted by the energy source 24 is adjusted as a function of the speed of movement of said batch 14 of objects in the bundling installation. .

The function of this adjustment step is to optimize the time of exposure of the film to the radiation emitted by the energy source. The invention will now be explained with reference to the illustrated embodiments.

Figure 1 illustrates in particular a schematic overview of a wrapping installation having a conveying plane 20 of a batch 14 of objects 16 such as bottles. The wrapping installation successively comprises along the conveying plane 20, a selection station 34, a coating station 36, a welding device 10, and a tunnel 32 for shrinking the film 12 on the batch 14 of objects 16 The succession of the above elements defines a direction of conveying the batches of objects in the wrapping installation, also called direction 28 of movement of the batches of objects in the wrapping installation represented by the arrow.

The selection station 34 is only represented by its downstream conveyor, which conveys a batch 14 of bottles which have just been formed.

A film supply 12, located below the conveying plane 20, has not been shown in FIG. 1. This equipment is designed to supply a series of sheets of heat-shrinkable film 12 for coating each batch 14 of objects 16 at the level of the topping station 36.

To do this, the downstream end of the film 12 is projected through a slot 38 called “injection slot 38” located between the downstream conveyor of the selection station 34 and the conveyor of the lapping station 36. The downstream end of the film 12 comes out of the slot 38, while the batch 14 of bottles goes up on the conveyor of the topping station 36. Thus the weight of the batch 14 of bottles pinches the downstream end of the film 12 between the batch 14 of bottles and the surface of the conveyor of the topping station 36. Then, once the batch 14 of bottles has completely crossed the slit 38, a coating bar 40 emerges from below the conveying plane 20 through the slit 38 and pulls the heat-shrinkable film 12. The topping bar 40 bypasses the batch 14 of objects while it is moving on the conveyor of the topping station 36. The film passes from the rear of batch 14 of objects to the top, then descends in front of batch 14 of objects. The film was previously cut to the appropriate size to surround the lot 14 of objects. The end of the cycle of the cycling bar 40 brings the upstream end of the film back to the batch 14 of objects. The upstream end of the film 12 then passes under the batch 14 of objects. Thus, the upstream and downstream ends of the film are superimposed under the batch 14 of objects, and thus form a zone 42 for covering the film 12.

Then, the batch 14 of bottles is transferred from the topping station 36 where it has been coated with a film 12, to the welding device 10.

In the embodiment illustrated in FIG. 1, the welding device 10 comprises a conveying means 18 comprising two conveyors with mobile interface positioned one after the other with respect to the conveying direction. Each conveyor comprises an endless belt 26 wound around two windings 30. The axes of these windings 30 are mutually parallel and transverse to the direction of the direction of travel of the objects. They are also included in a plane parallel to the conveying plane 20. With respect to the direction 28 of movement of the batches of bottles, the free space between the winding 30 downstream of the upstream conveyor 44 and the winding 30 upstream of the downstream conveyor 46 defines a window 22 through which the radiation emitted by an energy source 24 passes to weld the ends of the film 12. In this case, the window 22 is also called spacing. In general, the window 22 is rectangular in shape, the length of the rectangle of which is transverse to the direction of conveying the batches of objects in the bundling installation, and the width of the rectangle of which is longitudinal with respect to the direction of conveying batches of objects in the bundling installation. The radiation emitted by the energy source 24 is generally perpendicular to the conveying plane 20.

Once the ends of the film 12 are welded at the level of the overlap zone 42, the batch 14 of bottles is conveyed towards the heat-shrinking tunnel 32 to heat-shrink the film 12 around the batch 14 of bottles and thus obtain a self-supporting burden.

The heat-shrinking tunnel 32 includes heating members which make it possible to reach inside a temperature which is generally between 150 ° C. and 250 ° C. depending on the bundled objects and according to the type of heat-shrinkable film 12 used; generally this temperature is of the order of 200 ° C.

Alternatively, as illustrated in FIG. 2, the conveying means 18 comprises an axis of the winding 30 downstream of an upstream conveyor 44 and an axis of the winding 30 upstream of a downstream conveyor 46 which can move in a trajectory parallel to the direction of travel of the batches of objects on the conveying plane 20. Despite the displacement of these windings 30, the dimensions of the window 22 remain constant between the windings 30 downstream and upstream. The batch 14 of bottles positioned on this window 22 moves at the same speed so that the ends of the film 12 and in particular the overlap area 42 are always facing the energy source 24 which are both following the direction of scrolling. This energy source 24 can be mobile simultaneously with the movement of the window 22. The window returns to its loading point and synchronizes with the next batch of objects.

FIG. 3 illustrates an embodiment of the welding device 10 comprising an energy source 24 and a conveying means 18 in the form of an endless belt conveyor 26.

The conveying means 18 comprises an endless belt 26 wound around two windings 30 whose upstream and downstream axes are located transversely with respect to the direction 28 of movement of the batches of objects. The endless belt 26 can be made of a single material such as a canvas or a composite material or several links forming an articulated chain which can be plastic or metal or even a composite material.

At least one through groove is made in the mass of the endless strip 26. This groove is for example of rectangular shape whose length of the rectangle is transverse to the direction 28 of movement of the batches of objects in the wrapping installation, and whose width of the rectangle is longitudinal with respect to the direction 28 of movement of the batches in the wrapping installation.

The endless belt 26 comprises an upper strand 48 which conveys the batches of objects to be welded and a lower strand 50 used for the return.

An energy source 24 is positioned between the upper strand 48 and the lower strand 50. It is mounted on a support 25 which itself is mounted on a guide means 52 to give it the possibility of moving between the two windings 30 in a plane parallel to the plane defined by the upper strand 48 of the strip without end 26 for welding the ends of the film 12 at their overlap area 42. The energy source 24 emits radiation substantially perpendicular to the defined conveying plane, that is to say the plane defined by the upper strand 48. This radiation then passes through the groove made in the endless band 26 to weld the ends of the film 12 before making the batch enter the heat shrink tunnel.

At least one of the windings 30 is motorized, for example by a synchronous motor so as to constantly know the position of the endless belt 26. Therefore, it is possible to synchronize the position of the groove with the position of the energy source 24, of the batch and of the area 42 for covering the films.

FIG. 4 illustrates the embodiment described in FIGS. 1 and 2 of the welding device 10 comprising an energy source 24 and a conveying means 18 in the form of at least two endless belt conveyors 26 placed one at a time. following the other with respect to the direction 28 of scrolling of the batches of objects materialized by an arrow.

The conveying means 18 comprises an axis of the winding 30 downstream of an upstream conveyor 44 and an axis of the winding 30 upstream of a downstream conveyor 46 which can move in a path parallel to the direction of travel of the batches d 'objects. The space between the winding 30 downstream of the upstream conveyor 44 and the winding 30 upstream of the downstream conveyor 46 defines a window 22 through which radiation emitted by an energy source 24 passes to weld the ends of the film 12.

The upstream and downstream windings 30 are each motorized and controlled by a control unit making it possible to synchronize the movement of the upstream and downstream conveyor as well as the movement of the energy source 24.

Although the above description is based on particular embodiments, it is in no way limitative of the scope of the invention, and modifications can be made, in particular by substitution of technical equivalents or by any combination other than any or part of the characteristics developed above.

Claims (15)

1. Welding device (10) for welding heat-shrinkable films (12) coating batches (14) of objects (16) simultaneously with their conveying in a wrapping installation (1) comprising: - a conveying means (18) of said lots (14), the ends of the film (12) coating each lot (14) being superimposed under said lot (14), said conveying means (18) being able to move the lots of objects in the direction (28) scrolling of the batches in the wrapping installation and in a conveying plane (20), and - at least one energy source (24) by radiation capable of welding the heat-shrinkable film (12); characterized in that said conveying means (18) comprises at least one window (22) capable of moving with said conveying means (18) and in that said energy source (24) is fixed on a support (25 ) placed under the conveying plane (20) and is able to move in the same direction as said conveying means (18) and independently, so as to produce a weld through said window (22). 2. Welding device according to claim 1, characterized in that the energy source (24) is a source of electromagnetic radiation preferably emitting radiation in the infrared range. 3. Welding device according to one of claims 1 or 2, characterized in that the energy source (24) is able to move transversely relative to the direction (28) of movement of the batches (14) in the wrapping installation. 4. Welding device according to any one of the preceding claims, characterized in that the energy source (24) comprises a set of lenses capable of deflecting the radiation transversely with respect to the direction (28) of movement of the batches (14 ) in the wrapping installation. 5. Welding device according to any one of the preceding claims, characterized in that the energy source (24) comprises a plurality of generators of energy by radiation. 6. Welding device according to any one of claims 1 to 5, characterized in that the conveying means (18) is formed of an endless band (26) wound around at least two windings (30), said window (22) corresponding to a groove made in the strip, said groove being transverse relative to the direction (28) of movement of the batches (14). 7. Welding device according to any one of claims 1 to 5, characterized in that the conveying means (18) comprises at least one shuttle circulating on a guide means capable of moving said shuttle in the direction (28) of scrolling of the batches (14) of objects of the wrapping installation using a linear motor principle, said window (22) corresponding to a groove made in the shuttle and transverse to the direction (28) of scrolling of the batches ( 14). 8. Welding device according to any one of claims 1 to 5, characterized in that the conveying means (18) comprises at least two conveyors placed one after the other in the direction (28) of scrolling lots (14) of objects, the interface between the two conveyors being movable, said window (22) corresponding to said interface. 9. Welding device according to one of claims 1 to 5, characterized in that the conveying means (18) comprises at least two shuttles circulating on a guide means capable of moving said shuttles one behind the other in the direction (28) of scrolling of the batches (14), said window (22) corresponding to the space between two successive shuttles. 10. Method for welding heat-shrinkable films coating batches 14 of objects simultaneously with their movement along a direction of travel in a wrapping installation; said method comprising for each batch (14), a step of coating said batch (14) of objects with a heat-shrinkable film (12) whose ends of the film (12) upstream and downstream are superimposed under said batches (14) of so as to provide an area (42) for covering the ends of the film (12); process characterized in that it comprises for each batch, subsequent to the coating step, at least the following steps: -positioning at least part of the area (42) for covering the ends of the film (12) on a window (22) transverse to the direction of travel (28); -maintain the window under said overlap zone by moving it in the direction of travel at the same speed as said batch; and positioning a radiation energy source under said window and emitting radiation at the overlap area through said window (22). 11. A welding method according to claim 10, characterized in that during the step of emission of the radiation, said energy source moves in the direction of travel at the same speed as said batch. 12. A welding method according to any one of claims 10 or 11, characterized in that during the step of the emission of said radiation, said energy source moves transversely to the direction of travel so that the weld is operated over the entire dimension of said batch transverse to its direction of travel. 13. A welding method according to any one of claims 10 to 12, characterized in that the heat shrinkable film (12) used is a radiation absorbing film. 14. A welding method according to any one of claims 10 to 13, characterized in that it further comprises, prior to the coating step, a step of coating the ends of the film (12) with an absorbent material radiation, such as carbon black. 15. A welding method according to any one of claims 10 to 14, characterized in that, during the emission of the radiation, the power of the radiation emitted by the energy source (24) is adjusted according to the speed of movement of said batch (14) of objects in the wrapping installation.